QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 611 PM EDT THU APR 28 2011 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID APR 29/0000 UTC THRU MAY 02/0000 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR THE 18Z MDL RUNS WERE IN VRY GOOD AGREEMENT WITH THE 12Z RUNS..SO MADE ONLY VRY MINOR CHGS TO THE PRELIM DAY 1 QPF..BASED MSTLY ON RECENT SATL AND RADAR TRENDS/IMAGERY. DAY 1... ...SYNOPSIS... IN THE SHORTER TERM...THE MID/UPR FLOW REGIME WL REMAIN PROGRESSIVE WITH ONE TROF LIFTG NEWD AND OUT OF THE ERN U.S....WHILE ANOTHER TROF DROPS INTO THE NWRN U.S./INTERIOR WRN U.S.. MDLS ARE IN FAIRLY GOOD AGREEMENT. DEEP MSTR WILL QUICKLY BE SWEPT OFF THE ECST...WITH NOT MUCH IN THE WAY OF RETURN FLOW ON DAY 1 E OF THE ROCKIES. OVR THE NWRN U.S....EPAC IS MSTR WL GET CUTOFF RPDLY. PCPN OVR THE CONUS THIS PD WL REMAIN LGT. ...GRT LKS... DEEP VORTEX WL SLOLY LIFT NEWD ACRS THE REGION WITH SVRL EMBEDDED SHRTWVS THAT WL PROVIDE SOME LIFT. AFTN SFC HEATG AND WEAK SFC CVRG ZONES WL AID WITH FOCUSG SHWRS THRU THE REGION WITH LGT PCPN. ...ECST... DEEP TROF EXTENDING S FM THE GRT LKS VORTEX WL PUSH EWD WITH STG HGT FALLS...WHICH WL HELP PUSH THE SFC BNDRY/DEEP MSTR AXIS OFF THE CST TNGT AND BRING A WELCOME END TO THE THREAT FOR ORGANIZED HVY RNFL/SVR WX. MDLS ARE STILL SHOWING WEAK WAVES DVLPG ALNG THE SFC BNDRY THIS AFTN/EVE THAT SHLD TEND TO HOLD UP THE BNDRY...ESPCLY FM NC SWD INTO FL...THRU ERLY TNGT. LATEST MDLS AND SATL DERIVED PW DATA SHOWS AN AXIS OF DEEPER MSTR FM FL TO NC OUTERBANKS. THIS SHLD CONT TO FUEL ORGANIZED CNVCTN INTO ERLY TNGT...ESPCLY OVR THE OUTERBANKS. ON THU...ANY CNVCTN SHLD BE LIMITED TO SRN FL WHERE THE BNDRY WL HANGUP. SOME INLAND HEATG/CVRG SHLD SUPPORT A SMALL AREA OF ORGANIZED CNVCTN. MOST RNFL AMTS WL BE LGT. ...NWRN U.S... MDLS REMAIN IN GOOD AGREEMENT WITH THE TROF DROPG INTO THE REGION WITH DECENT HGT FALLS AND ASSOC LIFT. MSTR IS FAIRLY LIMITED THRU THE REGION AS EPAC MSTR IS CUTOFF VRY QUICKLY TNGT. MOST PCPN WL BE CONFINDED TO THE HIER ELEVS WHERE UPSLOPE WL AID WITH LIFT...BUT THERE SHLD BE A RIBBON OF MORE ORGANIZED PCPN ALNG THE 8H/7H BNDRY DRAPED FM THE NRN HI PLNS SWWD THRU THE NRN ROCKIES/WASATCH INTO NRN GRT BASIN. VRY COLD MIDLVL TEMPS COMBINED WITH SOME AFTN HEATG WL LKLY SUPPORT SOME CNVCTN THAT COULD ADD TO PCPN TOTALS. MOD TO PSBLY ISOLD HVY AMTS WL BE PSBL OVR THE THE HIER ELEVS OF THE NRN WASATCH AND NRN ROCKIES. ...NRN HI PLNS... SHRTWV ENERGY LIFTG NEWD INTO TO THE CAN/ND BORDER REGION THU AFTN WL HELP DRAW GULF MSTR NWD WITH A DECENT REGION OF LOLVL WAA DVLPG ACRS THE REGION. SFC BNDRY PUSHG EWD WL HELP POOL LOLVL MSTR WITH SHWRS AND PSBLY CNVCTN DVLPG THU AFTN THRU THE REGION. STILL ENUF UNCERTAINTY TO KEEP AMTS ON THE LGT SIDE AT THIS POINT. DAYS 2 AND 3... ...NRN ROCKIES/HIGH PLAINS EAST INTO THE UPR MIDWEST/GRT LAKES... A DEEP LYR CLSD LOW AND ASSOCD TROF AXIS MOVING INLAND ACRS THE PAC NW ON FRI WILL ADVANCE PROGRESSIVELY EAST THROUGH THE NRN ROCKIES AND OUT INTO THE NRN PLAINS BY EARLY SAT. ANOMALOUSLY COLD AIR ALOFT ASSOCD WITH THE HT FALLS WILL PROMOTE NUMEROUS OROGRAPHICALLY ENHANCED SHWRS FOR THE HIGHER TERRAIN OF THE NRN ROCKIES AS MID LVL LAPSE RATES WILL BE STEEPENING AND ALSO COINCIDING WITH DIURNAL HEATING. MEANWHILE...THE HT FALLS WILL BE DRIVING SFC LOW PRESSURE DEVELOPMENT OVER THE WY HIGH PLAINS WHICH WILL THEN LIFT NEWD THROUGH THE DAKOTAS AND INTO SRN CANADA THROUGH SAT. INCREASING SRLY RETURN FLOW AND ENHANCING MSTR TRANSPORT AIDED BY A 50 KT LOW LVL JET IS EXPECTED TO HELP SUPPORT A BKN AXIS OF LOCALLY HVY SHWRS/TSTMS ALONG AND JUST AHEAD OF AN ADVANCING COLD FRONT. THE MAIN FOCUS SHOULD BE ACRS THE UPR MIDWEST BY LATE SAT AND THEN ADVANCING INTO THE UPR GRT LAKES REGION SAT NIGHT WHERE ROBUST UPR JET DYNAMICS/DIV WILL BE IN PLACE AS WELL. ON SUN...THE COLD FRONT SHOULD REACH THE LWR GRT LAKES REGION WITH THE FRONT TAILING BACK TO THE SOUTHWEST OVER THE OH VLY...BUT ALL OF THE STRONGEST UPR JET SUPPORT/DYNAMICS WILL HAVE LIFTED WELL NEWD INTO ONTARIO. SO WILL EXPECTING MORE SCT SHWR ACTIVITY AND LIGHTER PCPN AMTS ASSOC WITH THE FRONTAL PASSAGE BY THEN. HPC QPF LEANED TWD A CONSENSUS OF THE 12Z ECMWF/UKMET AND GFS SOLNS. ...CNTRL/SRN ROCKIES...SRN PLAINS INTO THE LWR MS/OH VLYS... THE AFOREMENTIONED HT FALLS MOVING ACRS THE NRN TIER STATES WILL BE RESPONSIBLE FOR ALLOW A COLD FRONT TO MOVE DOWN ACRS THE SRN PLAINS/LWR MS VLY AND NEWD INTO THE OH VLY. HOWEVER...THE MID/UPR LVL FLOW IS EXPECTED TO BECOME PARALLEL TO THE BNDRY AND SO THE FRONT SHOULD SLOW DOWN...AND WILL LIKELY STALL OUT BY LATE SAT OVER PORTIONS OF THE LWR MS VLY. DEVELOPING SPLIT FLOW UPSTREAM WILL ALLOW A SRN STREAM UPR TROF TO EVOLVE OVER THE FOUR CORNERS REGION...AND THE LATEST MDL GUIDANCE SUPPORTS SHRTWV ENERGY AMPLIFYING POSSIBLY INTO A CLSD MID LVL LOW CENTER OVER SRN UT/CO ON SUN. THESE HT FALLS WILL BEGIN TO HELP INVIGORATE A NEW AREA OF LOW PRESSURE IN THE LEE OF THE SRN ROCKIES WHICH WILL THEN BEGIN DEVELOPING EWD ALONG THIS BNDRY TWD THE WRN GULF COAST BY LATE SUN. A RENEWED HVY RAINFALL THREAT IS EXPECTED TO EVOLVE SUN AND SUN NIGHT INVOF THIS FRONT AS VORT ENERGY EJECTING OUT OF THE BASE OF THE FOUR CORNERS AREA TROF INTERACTS WITH THE FRONT ALONG WITH INCREASING LOW LVL WARM ADVECTION/GULF OF MEXICO MSTR TRANSPORT INTO THE BNDRY. SRLY H85 FLOW OF 40 TO 50 KTS...PWATS RISING TO AOA 1.5 INCHES AND INCREASINGLY DIV FLOW ALOFT WILL BE CONDUCIVE IN ALLOWING AN ELONGATED SW/NE AXIS OF STG CONVECTION AND HVY RAINFALL. THE PATTERN FURTHERMORE IS CONDUCIVE FOR TRAINING/BACK-BUILDING CONVECTION WHICH WILL LOCALLY ALLOW FOR EXCESSIVE TOTALS. WILL CONTINUE TO MONITOR...BUT CURRENT THINKING IS THAT 3 TO 5 INCHES OF RAIN COULD FALL ALONG AN AXIS FROM NEAR THE RED RIVER VLY NEWD THROUGH CNTRL AR AND POSSIBLY INTO FAR SERN MO THROUGH LATE SUN WITH ISOLATED HEAVIER AMTS POSSIBLE. AMTS OF 1 TO 3 INCHES WILL BE POSSIBLE FARTHER NORTHEAST INTO THE LWR OH VLY AS FORCING AND MSTR TRANSPORT WILL BE INCREASING BY SUN EVE. HPC QPF AGAIN LEANED TWD A CONSENSUS OF THE 12Z ECMWF/UKMET AND GFS SOLNS. ECKERT/TERRY/ORRISON GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 30/00Z 0.01 506770 504762 500759 496758 491757 486753 491721 490711 489706 486702 478695 472693 468694 461694 458693 459690 462686 464683 465679 466671 463662 460657 458651 453647 448645 442646 438647 432652 425657 419662 405673 394682 369702 346721 323740 307755 286773 277780 269782 266783 260786 254790 248797 246802 246807 251818 256821 261824 266825 270827 280834 284835 288834 291832 300826 308819 317811 322808 327803 334799 336795 339794 349786 352783 355779 359776 366773 372773 377771 384767 392756 400746 412735 416732 419732 420738 420745 419752 417758 413764 410770 404777 401779 395785 391789 387794 382799 379806 377810 376813 379817 383819 379825 371835 366846 364852 363859 362866 363874 365883 368891 371897 378908 383913 389918 393918 396915 399909 399903 397892 395883 396874 398869 402864 406863 409863 414865 422871 425873 432876 438877 444875 450868 454864 463853 474843 483834 491823 498812 502804 505795 507781 506770 0.01 530184 532174 534163 533157 532153 529145 523131 521125 516119 508113 505110 503106 500099 496088 492082 485081 478081 474082 473080 476074 482063 485058 488051 496040 499036 505031 511025 516021 520016 523010 525006 525003 524999 522996 517993 514986 510980 502971 493966 484963 473960 467958 459959 453960 446963 436971 433976 432981 432985 433991 435995 438001 441004 443005 444009 443015 440020 430028 417030 414031 412034 409038 402048 392053 390060 385063 384067 384072 382071 379070 376072 374076 376081 379083 389090 392087 397090 400088 403091 402101 400106 397105 391115 391120 394124 406132 411133 411138 404146 400151 399157 400163 403166 407166 413176 421185 426190 429190 432185 429179 431175 434174 436171 435163 434160 437163 440167 443172 442178 438186 436192 437199 441204 440209 436210 429208 426212 427218 427224 430231 432233 428235 423234 422234 419235 417238 417243 421245 425250 448250 456251 463252 473254 485256 491259 495259 495254 494248 491242 488239 484238 482236 480232 478230 472232 470232 470227 472226 477225 483224 488224 493221 498208 505193 508189 511186 515185 519186 526188 530184 0.01 482195 482191 479185 474182 468183 465184 461187 458193 456198 456206 459207 465209 468208 473206 477203 479199 482195 0.01 430834 428831 425830 423833 424837 427839 430838 430834 0.25 516157 512146 504137 498131 490126 478121 475122 474124 472128 471132 471136 474139 480141 483144 488148 491151 500155 506155 511157 514158 516157 0.25 507008 506003 503997 500995 494993 489995 485997 482002 484011 485015 487019 487024 490024 495023 499021 502017 507012 507008 0.25 426685 423683 417684 408689 398697 387704 368718 358725 351732 333748 318761 302776 295783 291786 286788 281790 276791 265793 261796 256800 255803 256810 259815 263817 269814 286815 290817 293816 295814 300807 303803 308800 316799 325793 334786 350773 366758 375751 378747 383743 391735 396731 401725 408717 414708 421695 426685 0.25 477107 472104 465106 463103 462098 461093 463078 459065 455063 448063 444064 441068 440072 441076 444080 448084 447088 444087 438088 434090 430089 427092 429098 431100 429102 424103 420107 418110 415110 412105 409098 406100 405106 403115 405122 414121 427122 432120 437120 445127 448130 451130 455125 458119 464106 473113 476110 477107 0.25 463225 464221 463218 458217 452216 449217 443218 440218 436221 439225 444226 449229 453231 456230 459227 463225 0.25 452192 454189 453184 450181 448183 448187 449191 450192 452193 452192 0.25 420166 422162 422158 421154 422150 421146 418143 418146 416149 415153 415157 415161 416165 416167 420166 420166 0.25 422142 422139 422137 420138 419142 421146 422142 0.50 493144 493140 492137 489135 489134 486133 485134 484138 486140 489142 490144 491144 493144 0.50 400713 399710 394711 385715 376721 367727 353739 339752 329765 327768 326774 333776 338775 342772 350767 363756 371749 377743 391730 400713 400713 0.50 456110 456105 456101 456098 455097 453093 450094 447096 446097 444099 441100 442104 443109 444109 446111 447113 449116 452115 453114 455110 456110 24HR QP VT 01/00Z 0.01 558895 557881 555866 553860 550854 549852 548854 544860 542865 541871 538875 533879 528881 524878 522874 518867 512863 505859 500853 496846 494841 489832 483823 478820 472818 466822 464843 463849 461854 458861 454866 451868 443870 434870 428872 423872 418875 413876 409879 402882 396888 379897 372902 367904 354914 343926 336932 330934 317936 316932 315926 312923 309921 303923 295928 292935 291942 293949 297954 298963 296966 296970 294974 294979 295987 296990 299993 304991 306988 311982 316977 329969 333969 337970 344971 350970 352967 358963 364959 369954 374947 379942 386938 394933 404930 407931 409934 407949 404960 404970 403981 398990 395996 390004 384016 382026 380032 379034 374033 372030 366029 363030 361033 359035 358041 361047 363050 369054 377056 380058 382063 384072 378075 377081 379083 384087 387087 387084 387083 393086 396090 402088 404089 404095 403102 400110 399114 402117 411119 416121 419124 420127 421130 419134 416142 416149 414153 413159 414163 418162 421159 422154 422147 425136 427128 432124 439120 440121 440126 433145 433152 435160 439167 445172 447175 450179 453179 456177 457169 459168 463169 478179 480184 485186 488188 490192 495194 501193 512198 516198 519196 523194 526188 530180 532164 532150 529138 527131 526127 525120 526112 525106 523100 522095 520091 517086 513083 511082 506081 498081 495083 493082 493076 494072 498064 503055 514040 525024 534007 542990 546978 547972 548963 553939 555928 556923 557915 558901 558895 0.01 484676 482671 478667 473666 468660 461659 458658 455660 455664 455667 458669 460673 459678 457682 453689 453697 458701 464700 472694 480688 482684 483680 484676 0.01 491252 492248 492247 491243 490241 488238 487237 485236 484236 481237 479235 479234 476233 474233 473234 472237 472241 472244 471245 474249 476251 479251 482252 485253 488255 491253 491252 0.01 487219 486214 482212 478212 473213 464212 458214 452213 449213 444215 440216 438218 437222 440226 444228 452226 462227 466223 469222 478219 484223 487219 0.01 452989 450989 447989 444990 444991 442993 439995 436999 434000 436003 439002 442000 443999 445997 447994 448994 450991 452989 0.01 271784 268781 265780 263781 257788 251795 245801 241809 240816 242822 244824 249824 253820 257815 262807 267799 269791 271787 271784 0.25 543962 543956 543949 540943 536935 535922 533912 530904 526898 522895 513884 503875 497871 493870 489869 482869 472872 458880 445883 437886 422942 420955 418963 416971 411983 409988 407995 406002 409007 413006 418001 424993 432983 437979 443976 456968 460966 467965 471965 477966 485964 489960 490963 491969 492981 491988 489994 486001 482006 478013 476020 476027 478033 484036 493037 498036 504031 513024 523011 529000 535988 540974 543962 0.25 498950 496948 493948 491951 490952 489956 491959 494955 497952 498950 0.25 481138 482134 480132 478132 475132 474133 473137 474139 477138 480138 481138 0.25 472158 472154 471149 471148 470145 468142 465141 462141 460143 459144 458147 456151 457156 458156 461157 464158 467159 470160 472158 0.25 474111 474106 473102 470099 467096 464098 461100 459099 453097 452097 451101 452105 452109 452113 455115 461116 464118 467118 470118 471115 474111 0.25 457085 458080 458076 458072 456068 453067 450066 447064 446064 444063 443064 441066 441068 440072 441075 442076 444078 447080 447081 450084 451084 453087 456087 457085 0.25 361934 361930 358928 356927 353929 349933 345935 340939 337939 333943 333947 335950 339952 342952 348952 350950 355946 358942 360938 361934 0.50 539963 539957 538954 535950 529946 527943 526937 525918 525914 521906 517901 514898 508894 503889 500884 496881 492879 486878 479879 473883 461890 450893 447895 442899 439904 438911 438920 437929 435932 433940 430953 425964 420977 417982 416989 418990 422986 428976 433972 436969 440968 445966 449963 454960 459955 464949 463945 464944 468941 472940 480934 487931 494931 505933 509939 511946 509952 506957 503962 501967 499977 498984 495994 492001 486010 484015 483018 483024 487028 492030 497030 501028 505025 513017 521006 527997 533984 537973 539963 0.50 351943 351940 349939 346940 343941 340942 338942 338943 337946 338947 341948 344947 347947 350945 351943 1.00 530980 530975 528971 525967 519969 513972 509975 504985 503991 502999 501006 498013 495017 496021 504016 509012 513007 518001 525991 530980 1.00 472908 472903 470904 468905 467909 468909 471909 472908 24HR QP VT 02/00Z 0.01 555902 553892 551883 549879 546868 539852 537843 535832 534827 532823 529819 522808 515798 510795 505793 501790 499785 498778 497775 487772 476767 472767 466770 453775 433780 415779 410778 405773 396768 389763 385764 383767 383772 380783 380789 381797 379806 376818 376825 374831 367841 361851 359861 358866 357871 352879 348887 342897 339901 335905 329914 322923 319927 317932 315937 315942 313946 310948 298962 294966 292973 292981 293984 295985 299988 303989 307992 310998 315005 321005 326002 332996 341991 346989 350982 356974 364966 368957 373949 381944 386939 388935 393926 395921 399916 405911 409910 432902 443901 450900 457899 466901 473903 477905 479908 483917 485923 488931 489935 490943 485953 483958 481962 482967 484973 485978 488982 494990 497991 504991 511990 515989 517987 526978 540961 542958 543953 545946 549930 552914 555902 0.01 482663 481659 479655 475652 467649 458645 452645 450649 449655 449662 448667 444676 443681 445689 449691 454691 458693 461692 466688 471683 474675 478674 480672 482668 482663 0.01 526092 526077 522072 517068 512064 506058 476042 453018 443007 436002 427997 425996 421997 415001 411004 410009 408021 405029 403034 399035 389038 386037 383034 378028 374022 373017 374011 376002 378996 378992 377989 374989 367993 362998 358002 354010 346016 343022 341032 338040 335050 337062 333068 335074 337076 353083 359087 367090 375094 378097 383096 389094 392090 396089 398088 400085 402081 405079 410079 415076 416072 415070 414067 415065 413059 411056 412051 413041 415037 419035 425035 427039 428046 427051 424057 426065 439078 442080 444083 447086 447089 445093 443092 441090 438089 435093 435100 433104 433108 435112 439114 445117 454118 458114 461114 465116 468118 471117 475114 480106 482103 486102 495101 505104 512105 521097 526092 0.01 457160 456154 455151 457143 458137 457133 454130 452130 450132 448138 448142 445145 439145 435146 434152 435156 438157 444157 448163 453163 457160 0.01 429124 429120 429119 426115 423115 420113 417112 415112 412112 409112 406114 404117 406119 407121 408122 411122 414124 417125 420126 421127 422127 425128 427127 428126 429124 0.01 394117 394113 391112 389112 386112 383116 382119 380123 380126 382129 385129 388128 389127 391125 392124 393120 394117 394117 0.01 266799 263796 260795 256793 248796 244801 242806 241813 241819 242822 245823 248822 251815 253811 261807 265803 266799 0.25 542902 541896 540889 539880 537873 536859 533850 528840 524834 518828 513824 506820 499819 493818 487819 479821 470826 463831 462834 461841 459847 454854 448860 445866 445871 447875 450877 454878 468878 474878 481879 493882 499886 504892 506899 506904 506915 502935 502947 504953 507955 510956 518956 523952 528945 535926 538919 541907 542902 0.25 405833 403830 398829 391831 386834 382837 379840 372848 368856 364867 361875 356884 353891 347899 336913 332921 329931 326939 321948 317953 309961 305968 305971 308974 312980 312987 314993 318995 322993 329986 336981 340979 342975 346968 354960 364945 368938 375931 380924 386914 390907 392902 394896 395887 400878 403869 404857 405842 405833 0.25 393799 392798 389799 386801 386802 387805 388806 391804 392800 393799 0.25 390076 386065 385055 382050 375043 371037 367033 362032 358037 353047 353056 353060 355064 360067 367067 371070 374075 377082 378083 387074 390076 0.50 397864 396860 395855 391853 386852 379855 372860 367867 361880 357888 353894 345906 341911 336918 331933 320960 317966 316976 317985 318987 321986 335978 340974 344967 348961 353956 361942 369929 377917 380911 383902 387886 393874 395867 397864 0.50 374050 372049 369048 366048 364051 361053 359054 361057 364056 367056 369056 372054 372053 374050 1.00 383880 383876 381873 376873 367879 356896 343913 338923 334933 331943 328953 324964 323968 323976 328977 334974 340966 345958 352950 362931 372913 379892 383880 1.50 373891 372886 367887 361894 352906 343919 336933 333942 331951 329959 328962 328968 332970 335967 340960 350948 357935 366918 369912 371902 373891 2.00 367904 366900 364899 357903 350912 344920 339931 335942 332954 331960 332965 340956 347948 352940 358927 363918 367907 367904 3.00 357917 359911 356910 354915 352920 349924 347928 345932 341938 339944 341946 346939 349933 352929 354925 355921 357917 $$