QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 620 PM EDT SAT APR 30 2011 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID MAY 01/0000 UTC THRU MAY 04/0000 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR UPDATE... CHANGES TO THE PRELIM DAY 1 QPF INCLUDED AN INCREASE IN PCPN ACRS NERN TX/SERN OK WHERE CONCENTRATED MOISTURE FLUX EXPECTED LATE TONIGHT INTO EARLY SUN. OTHERWISE...THE OVERALL HEAVY QPF AXES FROM NERN TX/SERN OK INTO THE LOWER OH VALLEY DID NOT CHANGE APPRECIABLY FROM THE PRELIM DAY 1 QPF. ORAVEC ...DAY 1... ...SYNOPSIS... MDLS ARE IN GOOD AGREEMENT WITH DVLPG A MID/UPR SPLIT FLOW REGIME OVR THE U.S. AS THE NRN PLNS VORTEX LIFTS INTO SERN CAN AND TRAILING SHRTWV ENERGY DROPS TWD THE SRN ROCKIES WITH A CLOSED LOW DVLPG. MID/UPR RIDGES WL DOMINATE THE WCST AND ECST. DEEP MSTR IS RETURNG INTO THE SCNTRL U.S. MUCH QUICKER THAN MDLS ARE FCSTG AND WL LEAD TO ANOTHER ROUND OF BIG RNFL THAT WL AGGRAVATE THE FLOODING SITU FM THE LWR OH VLY INTO THE LWR MS VLY. ...ROCKIES... TRAILING SHRTWV ENERGY DIGG SWD THRU THE REGION WL PROVIDE ENUF LIFT FOR GNRLY LGT PCPN OVR THE HIER ELEVS OF THE NRN ROCKIES/NRN HI PLNS...THEN BEGIN TO EVOLVE INTO A CLSD LOW AS THE ENERGY APRCHS THE 4-CORNERS REGION. THE SLOWER MOVEMENT AND CLOSED LOW DVLPMENT WL RESULT IN STGR MID/UPR DYNAMICS WITH AN INCRSG AREA OF LGT/MOD PCPN OVR CO INTO NM. HIER ELEV SNOWS WL INCRS WITH HVY SNOWS PSBL. ...NRN PLNS/UPR MIDWEST INTO GRT LKS... DEEP MIDLVL VORTEX OVR ND THIS AFTN WL LIFT NEWD INTO CAN WITH THE ASSOCD SFC LOW ALSO TRACKING NEWD. THE ATTENDANT CDFNT WL SWEEP NEWD THEN TRAIL SWD THRU THE MIDWEST/GRT LKS AND THEN SWWD INTO THE SRN PLNS. NOT MUCH IN THE WAY OF MSTR WL BE ADVECTED NWD INTO THE NRN U.S. THIS PD AND THE FNTL BNDRY WL BE MOVG RATHER QUICKLY...SO AGREE WITH MDL SOLUS OF LGT PCPN ACRS THE REGION. ...OH VLY SWWD INTO THE SRN PLNS... AFOREMENTIONED SFC CDFNT WL AT LEAST SLOW ITS EWD/SEWD MOVEMENT THRU THIS REGION AS THE MID/UPR FLOW BCMS ALIGNED WITH SFC BNDRY...AND A SFC WAVE DVLPS OVR TX AND BEGINS TO LIFT NEWD ON SUN TWD THE ARKLATX. THIS IN RESPONSE TO THE DVLPMENT OF THE 4-CORNERS CLSD 5H LOW. UPR FLOW IS FCST TO BCM MORE DIFL THRU TIME...WITH AN UPR JET COUPLET AND FINALLY STG ENTRNC REGION UPR JET SUPPORT PROVIDG STG/DEEP LYRD LIFT ACRS THE REGION. SVRL SHRTWVS ARE FCST TO LIFT ENEWD FM THE SWRN U.S. THAT WL PROVIDE POCKETS OF STGR LIFT. MSTR WORKING NWD FM THE EPAC/GULF/CARIBBEAN IS HIER THAN GUID INDICATES...WITH VALUES ALRDY INTO THE ARKLATX ARND 1.50 INCHES....WITH VALUES OVR MUCH OF ERN TX ARND 1.25 INCHES. MDL FCSTS SHOW VALUES INCRSG TO ARND 1.75 INCHES ALNG/NR THE FNTL BNDRY AS IT STALLS AND MSTR POOLS. MDLS SHOW A MOD/STG LLJ DVLPG TNGT THAT WL SUPPORT VRY STG MSTR FLUX WITH 8H MSTR FLUX ANOMALIES INCRSG TO 4-5 STDS ABV NRML TNGT...THEN BACKG OFF ON SUN MRNG...BUT REDEVELOPING BY SUN AFTN OVR CNTRL TX AHD OF THE NEXT UPSTREAM SHRTWV TROF. SREF/GEFS/EC ENSEMBLE SPAGHETTI PLOTS OF 1-3 INCH RNFL ARE IN AGREEMENT THAT THE REGION ARND THE ARKLATX NEWD INTO THE LWR OH VLY WL SEE THE HVIER RNFL THIS PD. LATEST GUID GNRLY SHIFTED HVIER PCPN SWD TWD THE MORE UNSTBL AIR AND STGR MSTR TRANSPORT. NAM QPF VALUES SEEM WELL UNDERDONE...WHILE THE EC/GFS/UKMET ALL ARE SHOWG SIGNS OF FEEDBACK WITH SVRL BULLS EYES OF HVIER PCPN FM NERN TX INTO THE LWR OH VLY. THERE SEEMS TO BE MORE AGREEMENT OVR THE ARKLATX REGION FOR THE HVIEST RNFL...BUT DID SHIFT THIS INTO SWRN ARK WHERE THE STGR MSTR FLUX IS AIMED...ESPCLY TNGT. INTERESTING VERIFICATION FM THE HVY RNFL THIS PAST WEEK SHOWS THE GFS OUTPERFORMED THE EC AT ONE INCH AND HIER PCPN VALUES. EC ALSO HAS BEEN SHOWG A LOW BIAS OVR THE PAST SVRL MONTHS. ...UPR OH VLY INTO APLCHNS... XPCT CNVCTN THAT DVLPS OVR THE LWR MS/OH VLY REGION TO LIFT NEWD AND TOP THE ERN U.S. RDG. THIS ACTVTY WL HAVE DECENT MOIST INFLOW...BUT WL BE ALSO PULLING IN SOME LOLVL DRIER AIR FM THE RIDGE POSITIONED ALNG THE ECST. XPCT DCRSG RNFL AMTS THRU THE REGION WITH ONLY LGT AMTS. ...SRN FL... MOIST SE FLOW COMBINED WITH AFTN HEATG/SEA BREEZE CVRG WL SUPPORT SHWRS THRU THE REGION WITH A GNRL UP TICK IN PCPN DURG THE AFTN WHEN HEATG PEAKS. ISOLD HVY RNFL IS PSBL...BUT MOST AMTS WL BE LGT. DAYS 2 AND 3... ...SOUTHERN PLAINS/LOWER MS VLY NEWD TO THE NORTHEAST... ANOTHER ROUND OF MDT/HVY RAINS ARE EXPECTED ALONG A QUASI-STATIONARY BNDRY EXTENDING FROM THE SATURATED LWR OH VLY BACK INTO THE LIKEWISE LWR MS VLY/SRN PLAINS ON MON AND TUES. A COLD FRONT PUSHING EWD BY A DEEP NRN STREAM TROF WILL STALL ACROSS THE SRN PLAINS/LWR MS/OH VLYS BY A STRONG BLOCKING SERN UPPER RIDGE. THIS WILL RESULT IN THE FLOW ALOFT TO BECOME PARALLEL TO THE BNDRY AND THE FOCUS FOR MDT/HVY RAINS WITH POSSIBLE TRAINING... PARTICULARLY FROM NERN TX ACROSS AR AND INTO SWRN MO AND UP THE OH RIVER ON MON. STRONG SLY INFLOW OUT OF THE WRN GOMEX SHOULD HELP MAINTAIN PWS AOA 1.5 INCHES ALONG THE BNDRY WHILE MID LVL ENERGY AND FAVORABLE UPR JET DYNAMICS WORK TO ACCENTUATE LIFT ALONG THE FRONT. BY TUES... THE SRN STREAM DYNAMICS WILL BEGIN TO PARTIALLY INTERACT WITH THE NRN STREAM TO ADVANCE THE SHORT WAVE TROUGH AND FRONTAL AXIS DOWNSTREAM. THIS SHOULD CURTAIL A POTENTIALLY PROLONGED PERIOD OF HVY PRECIP PROPAGATING OVER THE SAME AREA LIKE LAST WEEK... THUS EXPECT THE HEAVIER QPF TO TRANSITION ACROSS THE OH/TN VLYS INTO THE SOUTH. OVERALL... 2-5 INCHES WITH LOCALLY HEAVIER AMTS IS EXPECTED FROM SUN EVENING INTO TUE EVENING FROM NERN TX/NWRN OK THROUGH AR INTO THE OH/TN VLYS. OVERALL HPC FAVORED A BLEND OF THE OPERATIONAL GFS/ECMWF FOR D2/MON AND PREFERRED A BLEND OF THE LAST TWO ECMWF RUNS FOR D3/TUES. GIVEN THE ANTECEDENT CONDITIONS AND THE EXPECTATION FOR HVY RAINS ACROSS THIS REGION ON SUN AS WELL AS THIS FCST PERIOD... THERE IS A CONCERN FOR MORE FLASH FLOODING. ...PACIFIC NORTHWEST TO THE NORTHERN ROCKIES... A PROGRESSIVE PAC SHORT WAVE TROUGH WILL ROLL THROUGH THE NW ON MON AND THIS FEATURE WILL CONTINUE DOWNSTREAM INTO THE NRN ROCKIES/PLAINS ON TUES... AS RELATIVELY LOW HEIGHTS PERSIST ACROSS THE NW. SOME OROGRAPHICALLY FOCUSED QPF IS EXPECTED BOTH DAYS AS MOISTURE TRANSPORT FROM THE PAC REMAINS RATHER MINIMAL. ECKERT/MUSHER GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 02/00Z 0.01 553919 551905 548895 545882 543870 541861 537854 530843 524833 520826 517820 513814 508810 503806 501804 501799 499790 494786 489782 483780 474781 462781 441782 432781 421776 410770 400765 389762 383766 381772 380801 374820 368834 363846 358857 353865 347875 341884 336894 330903 326908 322915 320920 318926 315937 314942 312947 306955 299962 291970 283976 277988 288993 310994 316996 319999 327006 330007 333006 336004 344996 354987 362977 373957 380949 387939 393929 395923 396918 396909 397905 401903 408900 416900 427898 438901 457905 468907 480910 474924 472931 471939 470955 465969 464977 461984 460988 460994 461005 463012 467016 471019 478020 484022 488022 492021 498018 505016 511013 516009 526001 529998 532994 536988 539982 546968 548960 550950 551939 552931 553919 0.01 517157 518152 516148 513142 510137 504132 494123 491120 487115 486110 487104 490097 497089 498083 499080 503076 506071 506068 503063 503059 500054 497050 493046 487043 475038 464035 458033 453030 444023 440019 436015 429015 427016 427021 430028 433034 435042 437049 436052 433054 427052 424052 423055 424060 431070 433076 435081 434085 430084 424082 422089 425096 425100 421103 416106 412101 410095 406095 404099 404104 402106 400106 394109 391115 391117 394119 401121 413122 418126 420130 438120 442123 446129 449134 454136 462136 466139 466141 464143 463148 468153 476159 482162 486163 489161 491156 495156 504158 514160 517157 0.01 416064 415060 413057 410054 407053 395046 386037 382031 380026 380021 378013 374007 370002 366002 361004 357009 353015 351020 346027 343034 340039 330048 325053 326057 328060 333062 332068 334071 332073 329075 327078 328082 331088 335095 341097 341085 346084 350085 356088 360088 363086 367080 370082 372086 378087 383087 386090 389089 393087 396087 402083 404080 407078 412078 414076 415068 416064 0.01 275798 268795 262794 253794 248796 244799 241806 241816 243821 246823 251824 255826 261827 264828 267826 271823 269817 265813 264810 266806 270804 273802 275798 0.25 536959 538954 537949 537944 534940 533937 532930 531914 529902 525889 521879 515849 510842 503835 492827 482823 475822 468822 460823 459825 460829 459834 459841 460848 462855 465859 466862 463867 461870 460876 466884 473886 480887 488889 492892 495896 500903 502909 501916 497937 495950 494960 496971 493981 492987 493992 495996 500999 507999 516994 521989 528981 531975 533969 536959 0.25 428814 427809 425804 422800 413793 410790 406788 400789 396794 391799 389805 384815 378825 374834 365857 354875 348886 342896 337902 330913 326923 322933 319943 318949 317955 311965 308969 308974 310977 315980 318983 321986 324992 329995 333994 337992 343984 349975 362956 364951 366945 368933 369926 372921 379912 385904 391893 397883 402874 406864 409851 412845 415840 419830 421826 425820 428814 0.25 402061 400058 398055 392052 386049 381045 372033 366032 362037 356051 348061 350064 350068 344071 347073 351075 355075 361069 363067 367067 370068 372071 375076 379076 381074 385073 388076 393075 397068 402061 0.25 378061 377057 375057 372057 369057 367057 365058 367060 368061 369061 372062 375063 378061 0.25 344058 345055 344054 341053 338053 335055 338057 341058 344058 344058 0.25 256810 255807 256803 253803 251802 250802 248803 247804 246806 246808 245811 246814 248814 251814 254813 256811 256810 0.50 408832 406824 404821 401821 398822 396825 384838 376845 370852 366860 362867 353883 344896 338905 334912 327926 323936 321944 320953 317960 313968 313973 316974 320975 322979 327985 332987 337984 342978 350964 360949 364930 367921 371913 383900 387891 391882 393876 394868 391862 392856 394852 396848 400844 405837 408832 0.50 381054 381049 377047 374043 372041 369042 367047 364050 361053 358054 361055 366055 370054 375053 378054 381054 1.00 380881 377876 375868 370866 368868 360878 354888 340906 334916 329925 325936 323942 323949 323956 320962 324969 329974 334976 338973 341969 349959 353950 355935 360923 365914 372906 376898 377893 379888 380881 1.50 372899 362884 356890 350897 341910 333923 330930 326937 324945 326952 326962 326965 329968 335967 340961 345955 348952 348947 350938 352929 356922 361916 366910 371902 372899 2.00 367900 364897 363893 361890 358891 349901 346907 342913 337919 335923 328936 326942 327948 329953 330958 331962 334960 338956 342951 345944 346937 349929 352924 362913 366907 367900 3.00 342931 341929 339931 338932 337935 336936 334939 334940 334943 335943 338941 339939 340937 341935 342932 342931 24HR QP VT 03/00Z 0.01 507708 506699 503695 495692 483699 473705 463706 458709 452715 449717 445717 440716 430714 423718 413725 410728 408733 403746 401751 397756 394766 391778 386790 383797 381807 380813 378818 373828 371832 366836 358843 348851 341858 327870 308882 301888 295893 295899 298908 301914 301921 301924 299928 295937 290944 283951 273955 267961 260968 253976 253979 255981 263981 270982 273983 274990 272994 272003 272007 275010 292017 299020 308021 314022 320019 324018 330015 337009 344000 349989 353981 356974 361966 366962 369961 375959 381955 385953 388949 393943 396938 404918 407909 411899 417890 423879 428870 434858 439847 442837 448828 454819 460811 467799 471794 477789 478783 483777 494754 502732 507708 0.01 524256 521248 516238 513232 511225 510221 511217 518220 528227 531227 534225 535223 536215 538206 538191 533180 526171 520163 505154 494149 486147 479148 468149 464150 460154 454159 442174 440178 439185 439193 440198 441203 445206 451206 454205 458202 460202 461204 455211 440217 436220 434224 432229 428235 424243 423246 424251 425255 428260 437267 441273 446277 450280 461285 472289 481293 493297 498297 502296 509293 513290 0.01 479195 478193 476191 473190 470191 468192 467193 465195 463198 462199 462202 466200 469199 472198 475198 478196 479195 0.01 454080 453079 451076 450074 448072 447072 444072 443076 444078 446080 447082 450084 450085 451084 453083 454080 0.01 439092 438091 435090 433089 432088 430085 427084 426084 424085 423088 424090 425092 427094 430095 430096 432097 435097 437096 438094 439092 0.01 415045 415038 412035 409033 406030 400027 397031 399034 402038 405042 407045 411049 413049 415045 0.01 401067 401058 398052 394042 394033 394020 394015 390011 386011 382013 376013 370004 366002 361001 358002 356008 356014 359019 357026 353029 349033 350041 344048 342055 344062 344068 343072 344077 348080 358078 361079 366083 378085 383085 387082 398076 401067 0.01 383035 383032 383030 381028 380027 377026 376029 376032 376036 377038 380039 383036 383035 0.01 273829 273828 271826 269825 268824 266823 263823 260823 257824 255826 255829 256832 257832 259834 260834 263834 266834 268833 271832 273829 273829 0.25 490721 487717 484716 476720 466729 460737 454745 447752 444753 440752 436748 432746 423750 418753 416757 406775 400795 393813 390820 386827 380835 375843 371851 364859 358866 354872 349878 344884 340892 335899 323911 316916 310919 309926 311930 315928 319929 317937 313945 306962 301969 297974 292980 289985 292994 291000 294004 297007 305011 309012 315011 321006 331996 336988 339980 349964 359951 367938 373929 378923 384916 390908 399893 408879 414870 417861 419856 420850 420845 422841 428831 434824 440817 444810 446805 449801 457793 469778 473772 477766 480757 483748 485739 490727 490721 0.25 518273 520268 520260 518252 509236 502220 497214 491210 485209 479214 477217 481221 484227 482235 478243 476252 480262 482268 487275 495282 500285 506287 510286 513283 518273 0.25 509189 509187 506184 505183 503182 500180 497181 495185 497188 499189 502190 505190 508189 509189 0.50 515277 518269 519264 518258 513248 508240 502229 499223 496220 490218 488217 484218 489223 492227 496237 497245 494252 489261 489266 491271 499279 504282 508283 512280 515277 0.50 477736 474736 471739 470741 469742 466745 464748 462751 461757 463760 465759 467758 470756 473754 475752 478750 478745 476741 477737 477736 0.50 458776 457773 457768 454767 452769 449771 446772 443773 441774 438777 438779 439780 441782 443782 446783 449782 452781 455779 457777 458776 0.50 439800 439796 437795 434795 433795 431796 430797 429797 426799 424801 422805 420810 421814 424814 427814 429814 430814 430813 433812 435808 436806 437805 439801 439800 0.50 418823 417819 415816 412816 405820 402823 393833 386837 382841 378849 371858 355877 348884 344888 342893 336903 330911 324919 323925 324928 322939 317950 312971 311978 309982 301991 298999 305006 310008 315005 321998 326990 331980 339970 345962 349954 356945 364934 369925 375918 382909 386904 390898 394888 398879 405869 408863 410855 410848 412842 418823 1.00 514266 514262 514261 511259 510260 510265 513268 514266 1.00 401850 398849 395851 386853 375864 371869 364875 358879 353884 349888 345895 342901 338906 331918 329924 328932 323945 321952 320959 318966 317971 318975 322979 326975 331971 335966 343955 359932 365920 373908 380896 384890 387883 391869 400855 401850 1.00 314997 314993 312991 311994 311997 313998 314997 1.50 382880 383877 382873 380872 377873 369881 360887 352894 338909 334919 330930 323949 323955 323961 323968 327970 330968 333963 339954 351936 356929 361920 366910 371901 377892 382880 382880 2.00 375887 373886 368888 362894 356899 348903 343908 339911 338915 335923 333930 330938 327945 325953 326957 328961 330962 332959 336952 346940 355926 362911 371897 374891 375887 3.00 353922 353918 351915 348915 344917 340921 338925 338929 336933 334938 332943 332947 333947 338944 341942 344938 346934 348930 351926 353922 24HR QP VT 04/00Z 0.01 490655 487653 482655 471666 464669 460670 454673 448679 436696 429707 421716 416722 410725 402734 397745 393756 388765 385769 383774 380784 378790 375792 358808 349816 345827 339835 334843 321855 316860 312862 309866 303868 295873 290877 287882 280897 282903 282910 277918 269934 258951 254958 249965 237978 243987 247989 252990 262992 268992 272994 280997 284997 288995 295989 303985 307984 311981 317979 322976 325975 331972 342967 349963 357959 369943 372941 374938 377934 381925 386914 390903 400882 404876 408872 412868 436827 440817 445808 451798 454792 456786 459762 461747 462741 464736 468735 476733 482731 486725 500704 497688 494681 489677 492662 490655 0.01 521269 522261 520255 516243 505222 504218 505214 506212 510210 516210 520214 525215 530216 532214 535210 536202 536197 535191 533186 529176 526170 523166 520163 517158 517154 517144 523120 522115 520109 513101 508091 506086 503086 495091 485094 483097 482105 483112 485116 490125 486121 471119 462122 455127 451134 445138 443137 443133 445128 452121 455117 457112 458103 456094 455092 456085 458081 461078 465076 467069 468059 466056 465053 462053 454057 446061 443065 440071 439077 441082 444085 445088 441090 435090 432089 429091 427095 424096 421100 410102 409106 410109 414121 414130 412134 410141 409151 406163 406167 407169 413169 416168 418169 418172 415181 417185 422186 427182 430179 435179 439181 443186 449189 457189 463190 469188 478189 486196 487197 484200 476201 469205 462208 455215 452217 451223 452249 456251 462253 466252 471252 476254 479257 486263 490267 490271 493273 498279 501284 503290 507293 510291 515286 0.01 491234 491233 488231 486229 483227 482227 480230 482234 485235 488236 491237 491234 0.01 275805 274800 272799 265796 260796 254797 250800 246807 245812 244816 245820 249820 252818 256816 260814 264809 269808 275805 0.25 515272 516267 516265 516262 515257 515256 512252 511251 510249 507248 506249 506252 506254 506258 507263 507265 507268 509271 512273 515272 515272 0.25 526193 526188 525185 521179 517174 513171 509169 506166 504160 501152 497145 493140 489138 483138 479142 473155 472159 473162 477168 486177 491180 497183 505185 508189 519196 522197 525195 526193 0.25 498222 497218 496216 494213 493212 491210 488210 485209 484209 482210 479211 478212 479215 479217 481219 484221 487223 489224 492225 495226 498222 0.25 451736 450728 447722 443720 440724 437732 432742 426749 417754 411756 405761 398768 390775 387782 385793 383800 380805 377808 365819 344846 340852 336858 324868 318874 312881 309888 308891 309896 311899 311903 308909 299921 290934 280946 277951 272956 262966 256971 252977 253982 256984 264987 269987 279987 287985 293980 305971 312964 318963 324962 331957 337953 344949 353946 358940 364934 367926 371917 375909 382897 386890 392882 402867 407860 412852 416845 419839 421829 426820 431813 436804 439796 441786 444767 446758 448749 451736 0.25 443109 442104 441104 440104 438108 441110 443109 0.50 496167 495162 493158 491157 487160 487161 487164 488166 490170 491171 492171 493171 496168 496167 0.50 433799 428794 421793 416795 411795 410794 409791 407786 407780 405776 401776 398776 395781 392787 389801 385807 381813 369825 362833 351843 349850 344856 341861 340869 335881 333885 332889 329892 319901 316906 313914 310918 306921 299931 290941 285950 283957 278961 268968 258976 257980 258982 265984 270984 278983 299967 307959 311955 316952 329944 341938 347936 351932 356927 360921 377899 390877 399864 408852 414841 416832 418825 421816 427807 429799 433799 1.00 396833 389833 383834 375835 370837 367840 357850 353855 349862 354872 351884 348891 344897 340902 340906 341907 337912 333917 324925 310928 302937 303940 306939 312937 321934 328934 335929 340924 343919 348916 370895 375890 379885 382880 383872 385868 388864 393858 396851 396845 396833 1.50 366886 367882 365879 364878 361879 361880 359884 357888 357889 361891 363889 366886 366886 $$