QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 523 AM EDT SAT MAY 01 2010 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID MAY 01/1200 UTC THRU MAY 04/1200 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR DAY 1.. LOWER/MID MS VALLEY TO OH VALLEY... AMPLIFIED PATTERN WILL BRING A PERSISTENT INFLOW OF DEEP GULF MOISTURE FROM THE LOWER MS VALLEY TO THE GREAT LAKES AREA TODAY AND TONIGHT....WITH MAX PW VALUES REACHING TO NEAR 2 INCHES. CURRENT BATCH OF HVY RAIN SHOULD GRADUALLY WEAKEN OVER THE TN/OH VALLEY AREA TODAY AS UPPER SUPPORT SHEARS NEWD. ADDITIONAL ENERGY EJECTING INTO THE PLAINS FROM THE BASE OF THE SWRN U.S. UPPER TROUGH SHOULD HELP TO TOUCH OFF ANOTHER ROUND OF HVY RAIN TONIGHT ACROSS THE REGION FROM AR TO THE OH VALLEY. RELIED ON THE QPF AXIS FROM THE GENERALLY CONSISTENT ECMWF WHICH AGREES REASONABLY WELL WITH THE GFS FROM AR/MS TO INDIANA. ECMWF/GFS SUPPORT WIDESPREAD 2-4 INCH TOTALS IN THIS REGION...WITH THE SLOW MOVING PATTERN SUGGESTING THE POTENTIAL FOR LOCALLY HIGHER TOTALS. NORTHWEST TO NRN/CNTRL ROCKIES... PAC SHRTWV ENERGY REACHING INTO WRN CANADA IS EXPECTED TO DIG INTO THE INTERIOR NW AND GREAT BASIN TODAY AND TONIGHT...REINFORCING THE UPPER TROUGH OVER THE REGION. THE APPROACHING IMPULSE AND ASSOCD JET DYNAMICS WILL SPARK WIDESPREAD SHWRS ESPECIALLY THRU THE HIGHER TERRAIN AS UNSTABLE CONDITIONS PERSIST WITH THE LOW HEIGHTS ACROSS THE REGION. LATEST MODEL GUIDANCE SUPPORTS AREAS OF .25 INCH PLUS TOTALS THIS PERIOD FROM THE WA CASCADES TO THE MTNS OF ID...WRN WY...AND NRN UT. NRN PLAINS... SLOW MOVING CIRCULATION WILL DRIFT NEWD FROM NORTH DAKOTA. WRAPAROUND MOISTURE AND ENERGY REACHING INTO THE WRN SIDE OF THE SYSTEM ACROSS ND AND ERN MT WILL CONTINUE TO SPARK SHWRS WHICH SHOULD BECOME LESS NUMEROUS TONIGHT AS THE CIRC BEGINS TO WEAKEN AND PULL INTO SOUTH CNTRL CANADA. MODEL CONSENSUS SUPPORTS SOME .25 INCH PLUS TOTALS OVER NERN MT AND ADJACENT NWRN ND. DAYS 2 AND 3... THE MOST OBVIOUS DIFFERENCE IN THE MODELS TONIGHT IS THE DAY DIFFERENCE IN THE TROUGH OVER THE EASTERN US. THE NCEP MODELS...SUPPORTED BY THE UKMET...MOVE THE MAJOR TROUGH PROGRESSIVELY ACROSS THE EASTERN US. THE EC...AND TO A LESSER EXTENT THE CANADIAN...SEPARATE THE NORTHERN STREAM IN A ZONAL FLOW FROM A DEVELOPING CLOSED CIRCULATION ACROSS TX WHICH MOREC EAST MORE SLOWLY. THIS DIFFRNECE HAS AN IMPACT OF THE QPF FIELD ACROSS THE SOUTH. HPC PREFERENCE IS TO FOLLOW THE GFS MORE THAN THE EC. BOTH MODELS HAVE HAD RUN TO RUN CONSISTENCY BUT THE NAM AND UKMET BOTH SUPPORT THE GFS AND THAT IS THE BASIS FOR THE MANUAL QPF...BUT TAKING INTO ACCOUNT SOME GRID-SCALE FEEDBACK ISSUES. FRONTAL SYSTEM FROM GREAT LAKES TO GULF OF MEXICO... MODELS ARE ALL IN AGREEMENT THAT HTERE WILL BE EXCEPTIONALLY HEAVY PCPN FROM THE LOWER MISSISSIPPI VALLEY ACROSS THE SOUTHERN PLAINS THROUGH THE TN AND OH VALLEYS THROUGH TO PA SUN AND SUN NIGHT...AND ACROSS THE SE STATES MON AND MON NIGHT...BUT NOT AS HEAVY AS DAY 2. THIS IS ONE OF THE RARE EVENTS WHICH CALLS FOR A MDT RISK OF EXCESSIVE PCPN ON DAY 2 AND STILL MAINTAINS A SLIGHT RISK ON DAY 3. THE CORE OF 85H WINDS OVER 30 KT WITH PW VALUES GREATER THAN 2 INCHES WILL PERSIST AHEAD OF THE FRONT THROUGH DAY 3 WITH A VIGOROUS LONG WAVE TROUGH. THE EFFECT OF CHOOSING THE GFS SOLUTION IN PREFERENCE TO THE EC IS TO MOVE THE QPF MORE PROGRESSIVELY THROUGH THE REGION. MANUAL QPF IS LESS THAN THE EC IN SOUTHERN AL DAY 3...AND THE EC HANGS ONTO PCPN INTO DAY 4. HPC LEANS MORE TOWARD THE GFS AXIS ON DAY 3 WITH A CORE OF QPF ACROSS NC SW TO MOB. NW STATES... THE TROUGH DROPPING INTO THE NW STATES FROM CANADA WILL NOT HAVE A GREAT DEAL OF MOISTURE TO SPREAD INLAND BUT WITH THE LOW INTENSIFYING MONDAY AFTERNOON AS IT MOVES FROM ALBERTA INTO SASKATCHEWAN THE FLOW WILL BE SUFFICIENT FROM THE PACIFIC FOR SIGNIFICANT PCPN ALONG THE WA COAST...CASCADES...AND NORTHERN ROCKIES OF ID. GFS AND EC ARE IN GOOD AGREEMENT AND HPC DID NOT MAKE ANY MAJOR ADJUSTMENTS OTHER THAN FOR TERRAIN FAVORED AREAS. HEDGE/KELLY GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 02/12Z 0.01 541202 540196 539191 536181 532172 528164 518150 513146 508141 504130 503126 504119 510098 517076 521067 526058 535043 537038 538034 540028 540023 546002 548997 549990 552981 553973 551966 550952 549941 545936 542937 539935 533932 528912 520894 517882 516874 515867 515861 515850 512825 511814 509806 508799 507794 505791 501788 496781 488777 483778 479778 476779 473777 472773 475766 479764 494754 499753 502748 504740 506731 505720 505713 503706 499702 496696 492692 472670 469667 467660 467656 467651 465644 462640 458634 455633 452633 448637 445642 442646 440650 438658 440679 441686 442692 445695 448697 450699 452702 453715 452721 450726 445736 442742 437749 431756 427759 423760 416761 411768 408774 405781 404786 402790 400792 393796 387802 379813 375815 367815 360814 356811 353807 352802 354794 356787 356782 352777 347779 344783 339787 332791 322795 317801 306812 301815 293816 291818 292822 296829 304839 306843 307853 308863 308872 304884 299896 290917 288924 288931 287948 285955 282960 275970 271977 270980 270983 274984 278983 282981 282987 284992 287998 291005 299007 310010 324010 333008 336008 339005 349995 365976 370972 376968 381964 386958 392945 400932 412905 430877 440862 444854 447850 452846 464845 471847 475849 479853 481864 484876 488887 489895 488899 485904 478909 472917 464930 459936 454943 452961 452967 454973 458982 461990 458001 452015 451018 448022 441027 438028 435033 433037 433041 436047 439052 441055 441059 439064 436066 432067 428058 427056 423054 416053 411053 409053 406051 404046 401044 395041 391039 386040 378041 371041 367041 364043 361043 357046 352058 357059 362060 367060 369058 373057 375057 378061 375063 366064 370071 371078 373085 375089 378090 381090 383096 387097 391094 398093 406091 409087 410083 417080 423073 431068 433072 432075 428080 423084 421094 421100 421103 418107 415107 415104 410096 408095 405097 403102 399103 394105 389109 385112 383115 379121 376130 378135 382136 386135 391136 393139 393143 395147 397146 405144 407136 410129 413128 417129 416137 413152 413159 414164 417166 420166 425158 427150 433130 437124 441125 443129 444134 444138 436140 434143 433148 432151 432155 434160 437163 442166 445173 445180 442182 442187 445190 446195 450200 454198 458194 461189 464187 467183 470181 474182 479187 481191 478194 476196 469201 464202 461203 459205 455211 438214 433213 430209 425206 428219 424221 424225 426233 416237 415243 422248 431251 439251 451248 458246 463246 472248 477251 482253 486257 490260 492262 491265 492273 495281 498284 500287 503286 507285 510283 511280 516270 519264 523262 0.01 357121 354113 352107 351103 351096 352091 356089 357085 357082 353079 350077 342075 338075 335076 333078 331082 330088 333099 338108 343116 346119 349120 351122 354122 357121 0.01 316032 313029 307028 301029 298031 292039 288047 285058 283064 277065 271063 267061 258058 248060 245063 243069 245074 248077 256081 274090 282094 288095 293094 297092 300088 302081 302075 302068 303063 307052 312043 315035 316032 0.25 513969 512965 509962 506962 503963 501966 499972 498977 497986 495991 494996 493001 495004 498000 503995 506991 508985 510979 512974 513969 0.25 500050 501036 499031 496030 487030 484028 476032 473038 470047 470056 473060 476064 482067 487067 491066 497059 500050 500050 0.25 474220 473216 470217 466217 463218 460220 460221 463224 466223 468222 469221 472220 474220 0.25 476163 476159 472154 470149 466144 463144 459145 456145 454147 452151 450159 452164 455162 461161 467163 470165 472164 476163 0.25 445810 441798 440795 434794 425792 421791 418792 416795 409803 404807 397811 392814 389817 383827 376834 366843 361847 354849 349851 347853 322885 315894 309903 304911 303916 303923 303935 303939 304946 307950 310953 318956 324958 330958 336956 343953 358941 372924 380916 384907 387902 390898 398890 405882 411874 426854 432846 438835 441830 444821 445810 0.25 460181 461178 460176 458177 456180 456181 459182 460181 0.25 446109 444105 443105 441104 440104 438106 436108 438110 441111 444112 446109 0.25 416118 416115 414114 412112 410110 409106 408106 406108 405110 403113 403115 403117 405119 408119 411119 414119 416118 0.25 410068 407067 405068 407070 410070 410068 0.25 376050 375049 372049 369050 369051 372051 375051 376050 0.50 432817 429810 427807 423806 417809 410815 401819 395821 388829 376841 362855 355861 347866 340871 334878 323891 319897 317901 315907 317917 317927 317936 317942 319946 325949 330949 336947 343943 351937 356932 361926 373912 383899 388890 394883 407869 418855 424846 427839 431826 432817 1.00 416841 415835 413832 408828 402829 396833 384842 375850 366860 361865 356869 344877 336884 332890 328896 327902 328911 329927 330936 331937 334937 339935 345931 355922 364912 372902 379893 386883 395872 405861 409856 413850 416841 1.50 405845 405841 402840 396841 389844 383848 379852 372859 364868 360871 354875 345881 339887 333897 331906 332914 334920 336926 338928 341928 358913 365905 371898 377888 383880 391871 396864 401858 403854 405845 2.00 397852 396850 391848 382853 375858 370865 364871 358876 351880 345886 339893 336898 334903 334908 337915 340920 343921 348917 355911 360905 370895 380881 391866 395860 397852 3.00 387860 382861 379864 369872 360880 351887 343896 340902 340907 344910 350909 355907 360902 367894 374884 381874 386864 387860 4.00 369885 369881 367881 365882 362884 360885 357887 355889 355890 352892 351894 350897 350898 350901 352904 354903 357900 358899 359896 359895 361892 364890 366888 368885 369885 24HR QP VT 03/12Z 0.01 515664 512661 507653 505648 500642 497640 492633 488631 483630 479633 473638 467643 462644 457645 455648 450658 449684 445689 442692 436696 431702 425706 421707 413704 407704 404706 402716 398728 394738 385759 381768 375776 360795 336825 322841 307856 275879 260891 257895 256899 255904 256909 261916 264919 266924 269936 274943 281949 284950 290951 302950 307949 313948 322945 328943 332940 337938 343935 350929 358924 363919 365915 380901 383899 389895 395894 399894 409895 419898 428902 437906 444907 450905 457899 463888 468878 474867 480858 486847 492832 497820 501812 500781 499767 499756 499749 509722 511710 512706 515702 516697 519694 519689 519686 518680 515667 515664 0.01 541202 533182 531169 529164 525161 522159 520154 518150 516143 518139 521134 522129 521125 519114 517109 511100 505092 504091 503087 503078 504071 505067 511059 514058 520054 526048 529042 531034 531028 533011 533999 531995 529986 526977 523965 523957 524953 527946 530941 533935 534931 535925 535917 535900 535894 537889 537875 536861 535852 533845 527840 518837 514840 508848 506853 503855 500855 495858 490865 489875 485887 482898 477911 474920 468961 465972 463977 464984 465995 468009 472020 467028 464031 459031 452028 443024 437020 423005 417000 410997 407995 409987 420974 430958 434951 436945 437941 433935 429933 426933 418936 411942 403947 397948 394946 389939 386938 383940 378946 375953 369969 367978 366984 369990 377003 376008 374012 371020 369029 366030 365033 363036 361044 361049 358052 356057 354060 350061 346065 341061 339057 335055 329052 323054 321058 323065 326072 327080 324086 321088 320094 324100 325105 327108 336111 340113 343119 351123 358120 365124 370121 374122 374126 375132 377134 381143 384144 386142 387135 391131 394130 396128 400127 406129 413127 417129 418134 419138 418142 417155 418160 420162 422157 424149 425138 430131 434122 436120 439120 442138 439141 437147 438158 440161 442161 444162 446166 447191 448197 454197 460193 467188 475187 478191 478195 471198 456205 450208 443212 436216 433220 430221 428223 429227 431231 431237 426239 426245 427248 431252 434256 440256 448258 452265 456269 461271 466276 473284 479292 486297 489300 493301 498302 510299 0.25 522265 513247 511241 510234 505225 504221 501215 494209 484206 477208 473211 469212 461215 458216 453216 450217 446220 444234 445241 448243 457247 467252 474256 484260 490267 496277 501285 506286 512284 517280 0.25 528208 529203 529198 529190 526184 524178 521172 516167 508158 505154 501155 497153 494148 492139 489135 484131 478130 474131 472133 473138 474141 480142 486146 489150 493150 495152 496158 493159 490158 487158 484158 481156 477152 472150 470147 467145 464146 463150 462155 464160 466166 470168 475167 484170 503187 509195 519204 522206 524209 528208 0.25 467715 465711 461711 454713 445719 440725 435732 429739 412743 406746 402753 395767 387780 382788 376795 357819 346831 336842 326853 316863 296883 285894 282899 279906 276911 276915 277919 281925 288930 299934 306935 316933 330931 338928 345924 367904 378893 388879 397867 405853 416841 421835 428829 431831 432834 434840 437845 443848 450850 458851 466849 471842 473836 474826 472812 470800 467790 466783 464776 463773 465769 468766 471758 470747 468738 465730 465721 467715 0.25 463178 463175 460174 458177 456181 459183 460182 462179 463178 0.25 412114 409110 409109 408110 407114 409116 411115 412114 0.25 401042 400037 397033 392034 389037 386041 383044 381049 381051 384054 389055 395054 398052 401046 401042 0.25 381075 378072 378071 376072 375073 375075 375076 378078 381075 0.50 515267 516263 514257 513252 510248 509240 507235 503231 502224 499218 496216 494214 491213 486210 479210 471214 463219 461220 463222 466225 468225 478223 483225 487228 485232 482233 479232 476231 473232 470235 467236 461236 459237 460240 465243 474248 482254 487258 490261 497272 501281 504283 506282 509279 510275 511271 515267 0.50 522192 520189 518186 515185 513185 512185 511184 509183 506183 508188 508189 511190 514191 517192 520194 522192 0.50 451798 450787 447778 445773 443770 438768 433765 432761 433757 436750 436746 435746 425756 413758 406764 402769 395778 385789 378799 371809 362820 346838 329855 320865 312873 295889 288898 285902 283907 283911 284915 286918 291924 296927 301929 305930 313928 318926 332923 338921 345917 353910 363901 372893 380884 394863 401851 409839 416829 423819 429819 434821 445826 448827 452825 453817 451798 1.00 503271 502266 501265 498264 497264 498266 499269 500272 503272 503271 1.00 503243 502239 502238 500235 499232 498228 497227 496223 493226 494231 494232 495235 496239 498241 499242 501245 503243 1.00 491252 491248 489244 487243 485246 486248 488251 489252 491253 491252 1.00 485218 484217 484214 482213 480213 479213 476214 473215 475219 478219 481219 484219 485218 1.00 479243 479239 478238 476236 474237 474242 475242 477244 479243 1.00 416804 414797 413790 410783 407782 401783 396787 390792 383800 378807 368822 356836 349843 343849 330861 319873 306884 295896 290903 289906 289912 291916 294919 300922 308924 313923 318921 328918 336914 344910 352904 365893 372887 377880 388864 397849 401841 404833 416804 1.50 407804 406798 404793 400793 396795 389801 383808 365832 355843 343854 336859 331864 321875 310885 301895 296901 294907 295913 297915 303918 309919 318917 333912 341908 347903 359895 371884 380871 388859 395845 399836 401829 406813 407804 2.00 403810 402804 399802 391806 379817 361840 352849 341858 321879 311887 306892 303897 300903 299906 299911 304914 308916 311915 327912 333909 340905 350897 363888 368884 373878 381866 388854 392847 394841 399826 401819 403810 3.00 397817 392816 386819 380823 376827 368837 359845 343861 326877 317886 314890 311895 308900 308905 312908 318908 325907 331905 342899 351892 361884 366880 369877 377867 384857 389846 394834 396827 397820 397817 4.00 392831 393826 391823 390824 387826 384825 382827 369840 353854 341866 326880 322885 318893 317897 319899 322899 327899 332899 339897 348891 354885 361879 369873 376864 380858 387848 389840 392831 5.00 384846 384840 383835 380835 377837 366846 359851 353857 344867 334876 330880 325887 328890 335891 340891 346888 351883 358878 363874 368869 377857 381851 384846 6.00 378844 374844 369847 361852 354859 348866 342872 335879 332882 332885 334886 339885 344882 352877 361873 367865 371858 377848 378844 7.00 367856 365855 362856 359858 358859 357861 355863 354864 354868 356870 359868 361866 362865 363862 365860 366859 367856 24HR QP VT 04/12Z 0.01 555129 555120 554114 552098 550092 549085 546075 539063 536058 534052 530036 527022 523005 522980 521971 519961 515947 510931 508920 509909 511896 513889 515885 516880 516875 513856 514845 511830 508817 505799 502792 499786 496778 494770 493754 494745 495736 496722 497709 496695 494685 493677 487662 484659 481658 474654 468660 464659 462660 459663 458669 459677 457681 455686 451692 449695 445695 442685 437674 433667 428660 426653 422647 418644 415645 413649 405657 401661 396662 390665 385668 380676 376684 373694 371698 368701 362708 353715 343724 339727 337732 334741 330751 325759 314776 292808 287814 283822 280829 279837 280845 281858 281863 279868 272874 267878 264881 260890 261912 264915 268916 277919 281923 281931 281937 283944 288949 296951 311954 319956 330956 336956 340958 344962 348963 354955 361945 369927 374920 379917 382920 392942 400945 404947 406948 409946 415941 419939 422937 425931 426926 427919 427911 428905 433902 438900 442897 450888 454884 457879 463867 469860 474859 478866 480872 480878 480896 480901 481909 483924 488936 490939 490943 481949 478954 475959 473964 472971 466997 462009 458022 443038 437046 431056 433080 423095 413107 410111 410119 411123 411130 410139 407144 401152 397157 398159 407167 414174 419175 421169 428162 431162 434164 438168 441171 444177 445179 441182 437192 437197 438204 437210 434213 427217 422221 420225 420229 422234 419236 416238 414246 413251 415256 419260 423262 431260 440255 447255 452259 457262 461266 470272 473275 477277 483278 489281 494286 504291 510290 514286 523261 523260 521255 520254 518253 518249 518244 518239 520235 521235 524231 524230 528228 531224 534221 535220 0.01 467715 464710 459713 456718 455724 454727 452729 450734 451740 450744 448746 446749 445753 447754 449750 454745 459741 462737 463734 466732 467728 467719 467715 0.01 437128 434127 433128 434131 437129 437128 0.01 432136 432132 431131 431132 428135 427135 428137 431137 432136 0.01 375868 370868 363872 352879 345887 340890 335895 334900 336909 338916 340919 343920 346920 351916 361909 364907 365897 365892 366886 372875 374872 375868 0.25 483703 481699 480699 480700 479704 478706 481709 482705 483703 0.25 537122 539115 539108 537095 535083 531072 527064 523056 518056 515059 511063 509068 506075 505078 504087 507114 508122 507128 506132 499138 494137 492134 487130 478126 469128 460127 457129 454132 451139 440153 441157 443160 448167 452174 453184 456185 458183 461181 463177 465174 470173 475173 480175 486179 494184 501190 511191 519194 523193 525187 526179 526171 526163 526154 529143 532135 537122 0.25 498227 499217 498207 496203 493201 486202 480205 474207 458211 446215 440218 436225 434232 437238 444244 453246 461248 468248 476249 483249 486250 490249 492244 498227 0.25 462106 456102 453095 445092 438091 434096 432099 431104 430109 432115 436116 442117 449121 455118 457113 460110 462106 0.25 402799 400791 398789 389785 384784 382779 384768 384757 382745 375737 370736 365738 360745 355753 349763 344772 336788 331798 325806 314821 308829 302838 298843 294852 292862 287872 285878 284889 285896 287902 291904 297903 307901 312899 316897 325890 333884 345871 359855 373841 386822 390817 396812 400804 402799 0.50 532097 532092 532087 530082 529079 528077 526074 523076 522077 521082 521087 521091 522096 523097 526100 529099 532097 532097 0.50 503173 501173 499168 498168 499168 501173 503173 0.50 490220 492216 490212 485209 481209 473210 464213 452216 447220 445220 444224 445226 448228 456228 459230 459234 456235 452234 453236 460238 475242 477237 476235 474235 470236 466236 466231 468229 478225 484224 490221 490220 0.50 492162 492156 491149 489143 486142 483145 477148 472149 469145 467142 462140 459142 456145 453151 452155 454159 456162 461164 465164 469166 478167 487167 490166 492162 0.50 448109 448105 447102 446101 444097 443096 441096 440096 438098 435100 435101 434104 434108 435109 438112 441111 444111 446111 448109 0.50 376764 375758 373754 368745 362749 358759 352772 346788 342796 339802 335805 330807 326810 324814 321820 317826 310831 304837 300843 297851 297854 298858 297863 293870 291877 292888 293894 298895 304896 310895 325886 330882 336875 348863 357851 369836 373831 375823 378814 379805 378800 377795 374783 374773 376764 1.00 465221 463220 460219 457219 454218 454219 457220 460223 463223 465221 1.00 468153 467153 465152 463152 464154 467154 468153 1.00 366773 364772 361774 356779 352784 350791 349797 346802 339813 324833 317843 313849 310855 298875 299886 302888 306887 310885 316881 322878 333869 340860 349849 355840 362828 367817 368809 365801 363796 362790 366775 366773 1.50 362817 359808 354805 345815 340819 335825 327835 323840 319847 313860 310865 314871 317872 321871 325870 329866 338855 341851 346846 349840 354834 360822 362817 2.00 341829 337829 334832 330837 328840 326842 323847 321851 324855 328852 331848 333845 335842 339838 341833 341829 $$