QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 606 PM EDT MON MAY 02 2011 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID MAY 03/0000 UTC THRU MAY 06/0000 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR DAY 1... ...18Z UPDATE... RADAR CONTINUES TO SHOW THAT THE PCPN SHIELD ACROSS AR/SE OK/NE TX CONTINUES TO TRACK TO THE NORTHEAST WHICH PLACES IT NORTH OF EVEN THE 02/12Z ECMWF. THE 02/18Z NAM WAS A BIT FURTHER NORTH AND TRENDED A BIT HEAVIER THAN EARLIER RUNS RIGHT ALONG THE OH RIVER. TENDED TO FOLLOW THE MORE NORTHERLY AND SLIGHTLY HIGHER GUIDANCE IN THIS AREA. ALSO MADE A FEW ADJUSTMENTS OVER PARTS OF NY WHERE MODEL CONSENSUS WAS GROWING IN REGARDS TO 24 HR RAFL AMOUNTS EXCEEDING AN INCH THERE. REMAINDER OF THE FORECAST AREA WAS LARGELY LEFT UNCHANGED. ...ERN HALF OF THE NATION... MODELS AGREE THAT THE THE CURRENT RNFL PATTERN OVR THE CNTRL U.S. WILL BECOME MORE PROGRESSIVE THRU THE PD AS THE SHRTWV TROF CURRENTLY INVOF THE SRN ROCKIES IS SHEARED/EJECTED NEWD WITH TIME. THE ASOCTD COOLING ALOFT AND THE STG RT ENTRANCE REGION DYNAMICS INVOLVED WILL PROVIDE THE LIFT FOR TRIGGERING SHWRS ALONG A BROAD BAROCLINIC BAND INITIALLY LYING FM THE NORTHEAST TO THE SRN PLAINS. MODEL QPFS IN GOOD AGREEMENT EMPHASIZING AN AXIS OF MDT TO VRY HVY RAINS ALONG THIS FRONTAL BAND AND SEE LITTLE REASON TO ARGUE WITH THAT SCENARIO GIVEN THE STG ISENTROPIC LIFT THAT SHOULD BE GENERATED ALONG THE FEATURE. THE HEAVIEST TOTALS ARE EXPECTED THRU THE FIRST HALF OF THE PD INVOF THE LWR OH VLY WHERE THE TRAINING OF CELLS AND/OR CNVCTV AREAS ARE LIKELY GIVEN THE INITIAL PARALLELING OF THE UPPER FLOW AND LLVL CNVGNC REGION. MEANWHILE..BELIEVE MODEL GUIDANCE MIGHT BE A BIT SKIMPY ON THE SRN EDGE OF THE PCPN AREA INVOF THE TN VLY WHERE THE AFOREMENTIONED RT ENTRANCE REGION JET DYNAMICS AS WELL AS STG MSTR CNVGNC AHEAD OF AND INVOF THE ADVANCING CDFNT SHOULD RESULT IN WIDESPREAD SHWRS. THE GEM REGIONAL AND ARW MODELS ARE SUPPORTIVE OF THIS HEAVIER SCENARIO AND LEANED IN THAT DIRECTION FOR THE MOMENT. ...PAC NW... SHRTWV ENERGY DROPPING INTO THE NWRN U.S. WILL CONTINUE PROVIDE THE LIFT FOR GNLY LGT PCPN TOTALS THE PAC NW TO THE NRN ROCKIES. MODEL QPFS IN VERY GOOD ACCORD HERE AND DID NOT DEVIATE FM THEIR GUIDANCE. DAYS 2 AND 3... ...SE U.S. UP THRU MID-ATLC AND NEW ENGLAND... A STRONG UPR TROF TRACKING ACRS THE OHIO RIVER VALLEY WILL REACH THE APPALACHIAN MTN CHAIN BY 05/0000Z. THEREAFTER...THE H5 CLOSED LOW IS EXPECTED TO STRENGTHEN OVER NEW ENGLAND AS IT BECOMES NEGATIVELY-TILTED IN NATURE. CYCLONIC LOW-LEVEL FLOW SHOULD USHER IN AN ABUNDANCE OF WESTERN-ATLC MOISTURE INTO THE COASTAL NEW ENGLAND. PWAT VALUES OF THE ATLC AIR MASS WILL RANGE ANYWHERE FROM 1.00 TO 1.25 INCHES W/ STANDARDIZED ANOMALIES RANGING FROM 1 TO 2 SDS ABOVE NORMAL. THE SLOW MOTION OF THE UPR/SFC CYCLONES WILL HELP FOCUS MDT TO HEAVY RAINFALL OVER THE NE U.S. W/ THE HEAVIEST PCPN EXPECTED ACRS NRN ME DURING THE D2/D3 PERIOD. ADDITIONALLY...UPR JET DYNAMICS ARE FCST TO BE FAVORABLE AS LARGE-SCALE UPR DIVERGENCE ACRS THE RIGHT ENTRANCE REGION OF THE JET MAX WILL SLIDE ACRS NEW ENGLAND. GIVEN LOW 6-HR FFG VALUES ACRS AREAS OF THE INTERIOR NORTHEAST...A SLGT RISK FOR EXCESSIVE RAINFALL WAS PLACED FROM NRN VT INTO EXTREME WESTERN ME. FURTHER TO THE SOUTH...FRNTL PCPN IS EXPECTED FROM THE MID-ATLC DOWN THROUGH THE SE U.S. AND INTO THE SUNSHINE STATE. MUCH OF THIS PCPN WILL FOCUS DURING THE D2 PERIOD WHILE D3 BECOMES QUIET AS WEAK RIDGING DEVELOPS ALONG THE SPINE OF THE CNTRL/SRN APPALACHIANS. SOME LINGERING SHOWERS CAN BE EXPECTED ACRS THE SRN HALF OF FL AS SFC RIDGING TO THE NORTH WILL RESULT IN PREVAILING NORTHEASTERLY WINDS ACRS THE REGION. THIS WILL ENHANCE THE CHANCES FOR LIGHT SHOWERS TO DEVELOP ACRS THE FL PENINSULA. OVERALL...HPC FAVORED A SOLN COMPRISED OF THE 12Z ECMWF W/ THE 00Z ECMWF ENS PROBABILITIES USED TO PLACE SOME OF THE HEAVIER QPF AXES ACRS THE NORTHEAST. ...NRN ROCKIES EASTWARD INTO UPR GREAT LAKES... A SET OF HGT FALLS SPREADING INTO THE HIGH PLAINS WILL FOCUS A SHIELD OF PCPN ALONG THE FRONTAL BNDRY AS THE TROF ADVANCES TOWARD THE EASTERN U.S. INITIALLY...QPF AMTS WERE PLACED ON THE LIGHTER SIDE ON D2 AS THE LOW-LEVEL WAA IS NOT STRONG ENOUGH TO POOL THE HIGHEST PWAT AIR FROM THE GULF OF MX UP INTO THE CNTRL U.S. CURRENT FCST GUIDANCE INDICATES THE AIR MASS BEING ADVECTED INTO THE MIDDLE OF THE COUNTRY WILL CONTAIN PWAT VALUES RANGING FROM 0.50 TO 0.75 INCHES. HOWEVER...SFC CONVERGENCE ALONG THE BNDRY COMBINED WITH MID-LEVEL PVA ADVANCING INTO THE MID MISS VALLEY WILL HELP SPREAD A LIGHT TO MDT SHIELD OF PCPN FROM THE NRN HIGH PLAINS EASTWARD INTO THE UPR MIDWEST/UPR GREAT LAKES. HPC GRAPHICS FAVORED THE BETTER TIMING PRESENTED BY THE 12Z/00Z ECMWF AS THE 12Z NAM WAS RULED AS A SLOW OUTLIER. ...PAC NW AND UPR INTERMTN WEST... SHORTWV TROFING ADVANCING TOWARD VANCOUVER ISLAND WILL SPREAD PCPN INTO BRITISH COLUMBIA AND DOWN TOWARD THE PAC NW/UPR INTERMTN WEST. PCPN WILL BE LIGHT THROUGHOUT THE PERIOD W/ SLIGHTLY HEAVIER AMTS ACRS THE CANADIAN ROCKIES GIVEN SUFFICIENT OROGRAPHIC LIFT. KORTY/RUBIN-OSTER/BANN GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 04/00Z 0.01 508681 506672 502670 498668 493668 484671 480669 479664 474653 466646 463646 460648 457655 448682 444691 440697 437702 423723 417717 413716 411717 410721 399744 392764 386775 380786 377791 373796 365804 355809 351808 344811 341815 337818 335821 329824 319827 309835 303841 298851 294860 291871 289880 286889 285895 288899 290902 290906 287911 283918 279928 275938 271949 270958 271961 274963 280962 289958 294954 300951 303949 308948 308952 306959 305970 306974 308975 311974 328966 339960 342958 348954 354949 358945 360941 375923 382914 387905 393896 396891 399889 401890 408897 412900 417902 422903 429902 439897 442892 444887 442882 438878 429872 425868 421861 421854 425850 432841 440833 447821 452811 457799 461787 468774 472763 477751 480738 493726 498716 501709 503703 505698 506690 508681 0.01 540207 539203 538196 536185 528164 526154 524147 524141 522125 519112 514092 509081 503076 498074 493074 489077 486081 476095 470091 463096 461097 458096 455092 454089 456086 457081 457074 456070 453064 451063 436068 435073 439074 442076 444080 446085 444088 438088 434089 431088 427084 425083 422099 417103 414111 408111 406111 403113 406118 410119 414122 417123 417129 410145 403148 400151 400154 403157 407156 411153 413156 413160 414165 417165 420163 423165 425176 425184 423187 422191 426192 432189 434188 433184 431180 431176 433175 438173 441173 443176 440186 442190 445192 449195 449200 471178 478182 484189 487193 488197 480200 474203 467208 459211 450212 444215 442215 438219 439225 444228 450229 456232 451236 450239 450243 452247 455250 461251 472254 486266 488270 491275 494281 497285 504292 508293 513290 523258 519249 517242 515233 513227 510225 505218 500210 496204 494199 491198 498200 503199 507201 512208 517214 523220 531224 534226 0.01 491234 488233 491235 491234 0.01 445133 443127 440124 437123 431128 428133 427137 425143 422150 423158 427163 431164 432158 431156 430149 430144 432138 434135 438133 442134 445133 0.01 268802 263798 259795 255795 251796 247798 244802 242806 241812 244818 250821 255816 256810 259807 263807 268805 268802 0.25 471673 468672 465675 461683 456693 450702 440718 435725 431734 423749 417757 410762 406764 402769 399776 398785 393793 389798 382804 375810 365815 358818 352824 346830 341837 333847 330856 325863 321869 319876 313891 310896 305901 296914 288927 286933 283940 285947 289947 293946 300942 307936 312933 317932 321934 325939 333940 338939 345934 351929 357924 367913 377901 397874 402867 407860 416844 426833 432825 436818 443802 450784 464749 468741 472732 475723 477717 477712 475692 472678 471673 0.25 531204 529191 527184 524178 519170 516166 514164 511164 508166 505163 499160 493159 491156 488153 485153 474150 468145 464144 459147 456150 453152 448154 448158 449161 452163 455163 460162 466166 482169 486174 489176 499181 503183 506183 509186 514195 521205 524208 527210 530209 531204 0.25 518273 519266 517259 515254 512251 510247 507247 505253 504262 499265 497269 498274 502279 504281 507283 513281 516277 518273 0.25 511133 511128 510123 509119 508115 507114 505109 502106 499106 496108 496111 496113 497117 498122 499123 501127 504131 505132 507133 510134 511133 0.25 497222 496217 494213 491211 488209 483208 479208 473210 470212 467215 463219 463221 466223 469223 472222 477220 481221 487222 492224 495226 497222 0.25 494144 492139 489136 487134 486133 483132 481133 482138 483139 486141 487143 488146 491147 494144 0.25 480240 479236 477234 476233 475233 473236 472237 475241 478243 480240 0.25 319859 319852 316849 314851 309854 307857 305860 302864 300868 299872 300875 305876 311873 313871 317866 318862 319859 0.50 471707 470701 468697 466696 462698 450713 446720 441727 437733 433742 427754 423762 417768 412773 408780 404788 400794 397800 394806 386820 382825 378828 373829 367827 361828 356831 350836 345842 342847 336859 328872 326877 323882 315894 299916 294927 294935 295938 301934 306929 313926 320923 333924 348918 360910 371899 379890 388878 396867 401861 406854 413842 421829 430817 437801 449771 463741 466734 470723 471714 471707 0.50 483160 481159 478158 477157 476156 475156 473154 471153 469153 469154 470155 473156 474158 475159 476159 479160 481161 483160 1.00 448755 448751 445748 442749 440752 435756 433760 432767 433773 432778 431783 434783 437780 440774 442770 444765 446761 448755 1.00 416820 412817 406814 399818 395822 386833 379840 369849 366850 364848 363844 361841 358841 354846 347854 344857 340863 337868 338877 325894 326898 328900 333900 340898 345899 349903 353903 357901 366893 381877 391866 398857 404846 409835 413827 416820 1.50 401839 399833 398832 393835 388840 383846 379854 376860 374865 370868 367869 364868 360866 356866 354868 352873 350876 350878 352879 352882 352884 355887 359887 363885 367880 373873 380868 385866 390861 394854 397848 400840 401839 24HR QP VT 05/00Z 0.01 504636 502629 500625 497623 494618 487614 479616 468625 462630 446647 431662 425669 416676 406684 398689 393692 387694 380697 348713 332724 322732 317736 314743 314753 314758 315762 319769 324779 323784 320788 316797 312805 314812 315815 315818 313821 309825 302822 297822 294824 289830 286837 287847 283854 281859 281868 282878 285885 288890 291891 297891 303889 313885 327879 343871 361859 369855 379851 393846 404845 409843 412839 419821 422817 427814 436812 444810 451808 458803 463794 468784 472776 482753 496717 500706 502696 506683 508670 509662 509653 505640 504636 0.01 530209 532205 532200 532194 529187 527182 524178 520172 516169 510166 508169 507173 507174 509179 515185 515190 517195 519201 522206 524210 527211 530209 0.01 519274 520267 520262 518253 516248 513245 510242 506244 503257 499260 495260 490261 486269 485275 486281 489289 496294 502292 509288 513283 517276 519274 0.01 523087 524080 524072 520067 514062 507059 500059 497063 494072 492078 492086 494090 497095 502097 511099 515098 518096 523088 523087 0.01 517978 515959 513953 509948 504943 499940 486940 477940 464945 456947 449947 437946 425947 418950 415953 411959 408966 406981 407010 411045 411049 410052 403051 400051 398053 397056 398060 398066 396072 395076 399079 404081 410081 414079 417077 418073 423072 427074 431079 434084 433086 430088 425088 425092 427095 430100 432110 435115 439116 442115 449116 455117 461114 463108 464103 462099 459093 459085 462081 465073 462051 465045 469042 474036 477029 478015 483010 486006 489005 492005 499008 506006 511003 513998 515992 517978 0.01 499237 498225 499214 496209 491210 483207 475207 468208 466210 464217 467220 472220 478220 487222 490224 492229 495235 499237 0.01 496158 495142 493136 489131 481127 478126 475127 472128 469133 466136 457142 454146 454150 454155 458160 461161 469162 478166 482165 487162 490161 496158 0.01 479151 480146 477146 474150 476150 479151 479151 0.01 414122 417115 415109 412104 409099 409098 409094 406095 405098 406102 403106 400110 397110 396113 397117 400119 403119 408119 413122 414122 0.01 288813 288808 286804 282801 275800 269799 263799 260799 256801 253808 254812 255816 261819 268820 274821 279821 283820 287817 288813 0.01 289075 290070 289065 285062 279059 272056 266055 263055 259057 257063 258066 260069 265072 271075 277077 283078 288076 289075 0.25 500651 498643 494636 489633 484631 480632 473636 465643 456655 448665 439678 432690 427699 421711 416724 413730 409736 402744 393752 374770 367779 363790 361796 361803 360808 357814 351822 347831 345838 347843 351843 354842 360837 378825 390817 401808 409802 421795 429790 435786 445778 452770 461760 470746 476736 483724 488713 494698 498684 499676 500667 500656 500651 0.50 496660 495653 493647 489641 486640 483639 478641 470647 457661 451670 445679 438697 436705 431717 413747 402762 397769 393772 388775 380781 378788 377793 379798 382800 386800 395797 404791 414784 424780 431775 438770 447761 454755 460748 466740 478721 486705 489697 494683 496671 496660 1.00 489666 488659 486655 484653 479653 474655 467661 460672 455680 452693 447715 444724 437734 430741 423749 424756 427759 433760 436759 440756 442753 450743 457736 467726 473717 479705 483697 485691 487683 489675 489666 1.50 482668 477665 473667 469670 466678 464688 462695 460706 459712 459718 461720 465718 469714 473707 477699 479696 480690 482683 483679 483672 482668 24HR QP VT 06/00Z 0.01 493636 486627 479621 475618 471616 466616 461619 453623 445625 435629 431631 428631 412633 407638 405643 404654 401656 398658 389661 380665 371669 366673 360674 353679 348682 346686 344691 344697 344702 342706 335711 326719 320726 312733 306739 293756 282768 270781 261785 254788 245803 243809 240813 239816 239819 241822 243824 250828 260830 264828 266824 267818 274812 284801 298788 306781 314774 333761 349752 358746 369741 388732 398728 404726 408726 412729 412735 408742 404746 401750 398755 396761 399769 403771 408771 412772 414777 416780 419781 423779 434775 445767 451761 459753 477737 485728 489723 492717 497707 500698 501691 501684 501672 498659 497650 493636 0.01 520269 523261 524255 525244 527235 530224 532219 537206 538199 538193 537186 536181 534177 531170 525166 522161 514152 503142 492135 487133 479130 475129 472124 473116 476108 474104 473102 469100 462099 458101 449113 449116 450121 452126 452144 453147 456150 461148 466148 468149 468153 467157 465160 461163 456165 452167 451169 452176 454178 457177 466172 471170 476172 486183 493192 497196 500199 504201 505203 504208 501209 498205 492202 489201 487202 481203 477203 472206 465209 461211 458215 460220 465221 468220 471223 468228 464231 461237 457242 456247 458254 464260 466267 471279 475284 478287 481289 489293 498296 507296 513290 0.01 524923 524912 521904 518899 514894 507888 504885 500884 493884 489884 479879 466866 458859 453855 449852 442848 432846 428846 422847 411849 401852 395855 391858 386861 382865 378868 374872 368878 360887 355895 354902 355907 357920 358923 361928 377938 384937 387940 391949 393957 393965 394973 397978 400983 404985 408986 415986 427984 440982 461980 473978 484975 489974 496969 498968 504962 507959 513956 517954 520946 522935 524923 0.01 291046 291038 288034 285031 280031 276041 273045 267044 262042 255042 250045 247050 247056 250059 258065 265065 272064 278062 283060 289053 291046 0.25 487647 485642 479636 474634 470633 464633 458634 448637 436642 429647 424653 420658 418665 415677 413682 419685 427689 433691 435692 438696 439703 438710 437717 437724 438734 442738 447739 454738 459735 465731 475719 481708 485701 487693 490681 491672 491664 489653 487647 0.25 529204 530199 528195 526190 523187 518182 515180 512179 511175 507173 504173 504178 509183 512185 515190 519196 522201 524206 527207 529204 0.25 509269 512261 512255 510249 507244 504236 501231 497231 497232 499238 502243 504248 503257 499260 497264 500269 503271 507273 509269 0.25 484922 484919 484918 478911 471904 463896 456891 446886 436882 427880 418880 411881 404884 401886 398890 398895 399899 402905 405909 411909 420912 422914 424918 423926 421938 420947 423953 425959 427962 429963 439963 443962 446961 449957 455949 478941 482936 484930 484922 0.25 410688 411684 407682 403681 400681 394683 392685 386687 381691 376695 374697 374701 375705 379706 384706 390703 395699 398700 403696 408692 410688 0.25 367714 364711 358712 353716 348720 344723 339727 337730 336733 337736 343736 348733 353730 358727 363723 366719 367714 0.50 484656 480648 475643 467641 462641 455642 448645 440651 437659 435669 431675 431679 434681 441683 446689 450699 452711 453715 461716 469712 476704 480697 483688 485681 486669 485660 484656 0.50 430892 429890 427889 425889 423890 423891 422894 424897 425898 427898 428897 429895 430892 1.00 478666 476658 473656 468655 463655 460656 455661 454665 454672 458678 461681 465684 468685 474682 476678 478671 478666 $$