QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 534 AM EDT MON MAY 02 2011 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID MAY 02/1200 UTC THRU MAY 05/1200 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR ...DAY 1... 06Z UPDATE... 00Z ECMWF GENLY SUPPORTED PRELIM GUIDANCE..SO ONLY MINOR ADJUSTMENTS WERE MADE BASED MAINLY ON SATL/RADAR TRENDS. ...SRN PLAINS NEWD INTO THE ERN GT LAKES REGION... OVERALL..MODELS SHOW REASONABLY GOOD AGREEMENT WITH THE PROGRESSION OF SRN STREAM UPR TROF ACRS THE SRN PLAINS..AND SLOWLY COMING INTO PHASE WITH SLOWER MOVING NRN STREAM SYSTEM MOVING INTO THE WRN GT LAKES BY TUE MRNG. THE BROAD SWLY MID/UPR FLOW BETWEEN THE TWO WILL MAINTAIN MADDOX TYPE SYNOPTIC FF PATRN ACRS THE SRN PLAINS INTO LOWER OH VALLEY AS FLOW PARALLELS VERY SLOW EWD MOVING NE/SW ORIENTED FRONTAL BNDRY. RAINFALL AMOUNTS ARE LIKELY TO BE CONSIDERABLY LESS THAN THE PAST 24 HRS..BUT THE ADDITION OF WIDESPREAD 1 TO 2 INCH RAINS WILL CONTINUE TO EXACERBATE ALREADY SATURATED CONDS AND EXISTING FLOODING THROUGHOUT MUCH OF AR INTO THE LOWER OH VALLEY. THE MORE SIGNIFICANT RAINS WILL CONTINUE TO REMAIN POSTFRONTAL GIVEN WEAK CAPPING ALONG AND AHEAD OF THE FRONT..ESPECIALLY OVER THE SOUTH BUT SECONDARY SURGE OF HIGHER PWS COMING INTO THE WRN GULF REGION MON NIGHT..COULD BE ENOUGH TO HELP CONVECTION BREAK OUT ALONG THE FRONT NEAR THE GULF COAST..AND SOME OF THE HI RES GUIDANCE SUPPORTS THIS IDEA. OTHERWISE..WITH DECENT OVERALL SYNOPTIC SCALE AGREEMENT..USED A BLEND OF GFS/UKMET/AND 12Z ECMWF FOR QPF OVER MUCH OF THE REGION. EXPECT GENL SWATH OF 1 TO 2 INCH RAINS FROM SE OK NEWD INTO SW OH WITH EMBDD HEAVIER AMOUNTS LIKELY WHERE BETTER TRAINING OCCURS. ...PAC NW... MODELS SHOW GENL AGREEMENT IN SPREADING ERN PAC UPR TROF FAIRLY RAPIDLY ACRS THE PAC NW REGION ON MON. NOT A LOT OF MSTR IS ASSOCD WITH THIS SYSTEM..BUT DYNAMICS ARE MDTLY IMPRESSIVE ENOUGH TO SUPPORT A QUICK SHOT OF MDT SHWRS AND HIER ELEVS SNOWS ACRS THE REGION..WITH MAIN EMPHASIS OVER THE OLYMPICS AND WA CASCADES. THE GFS INDICATED A SLIGHTLY MORE SWD TRACK WITH THE VORT BY 36 HRS..BUT OTHERWISE MODEL DIFFERENCES WERE RELATIVELY MINOR..SO USED A BLEND OF CONTINUITY AND NAM ECMWF MOST AREAS. DAYS 2 AND 3... ...LOWER MS VLY NEWD TO THE MID-ATL/NORTHEAST... FOCUS FOR HVY RAINS WILL FINALLY MOVE OUT OF THE SRN PLAINS/LWR MS/LWR OH VLYS...SHIFTING N AND E BY EARLY WED AS UPR TROF MOVING OUT OF THE SOUTHWEST TODAY PUSHES ACROSS THE MS VLY TOMORROW...DRIVING THE FRONTAL BNDRY THAT HAS BEEN STALLED ACROSS REGION EWD...ALLOWING COOLER/DRIER AIR TO WORK ITS WAY INTO THE AREA. MODELS SHOW SOME PHASING OF THIS SRN STREAM TROF WITH THE NRN STREAM AS IT MOVES ACROSS THE MS VLY WITH A UPR LOW DEVELOPING NEAR THE GREAT LAKES LATE TUE INTO EARLY WED. STRONG DIVERGENCE ALONG THE RIGHT ENTRANCE REGION OF THE UPR JET WILL INTERACT WITH THE DEEP MOISTURE PLUME DRAWN UP THE E COAST BY VIGOROUS SWLY FLOW TO PRODUCE MDT TO LOCALLY HVY AMTS FROM THE UPR OH VLY INTO UPSTATE NY/NRN NEW ENG LATE TUE INTO EARLY WED. AREAL AVGS OF 1-2 INCHES ARE EXPECTED ACROSS THIS REGION...WHICH COULD PROVE EXCESSIVE AS SUGGESTED BY THE MOST RECENT FFG VALUES. UPR LOW WILL CONTINUE TO AMPLIFY AS IT MOVES ACROSS THE NORTHEAST ON WED INTO EARLY THU. LGT/MDT AMTS WILL PERSIST INTO EARLY THU ACROSS NEW ENG INTO THE STRONG SLY INFLOW AHEAD OF THE LOW. CONDITIONS WILL BEGIN TO DRY OUT HOWEVER ACROSS THE MID ATL AS THE DEEPER MOISTURE IS DRIVEN OUT TO SEA AHEAD OF THE TRAILING COLD FRONT. THERE IS STILL SOME DISAGREEMENT IN THE MODELS WITH RESPECT TO THE TIMING OF THE SFC LOW...PARTICULARLY WITH THE GFS WHICH IS FASTER THAN ECMWF/UKMET/NAM. THE HPC FORECAST LEANED CLOSER TO THE SLOWER CONSENSUS. ...NORTHERN ROCKIES TO THE UPR MIDWEST... MODELS SOME MODEST MOISTURE RETURNING TO THE NRN PLAINS/UPR MIDWEST BY EARLY THU...HOWEVER MUCH OF THE DEEPER MOISTURE WILL BE SWEPT EWD BY THE AFOREMENTIONED SYSTEM MOVING ACROSS THE EAST. THIS MEANS THAT A WELL-DEFINED MID/UPR TROF MOVING FROM THE NRN ROCKIES TO THE UPR MIDWEST WILL HAVE LIMITED MOISTURE TO WORK WITH AND THEREFORE EXPECT MAINLY LGT AMTS TO BE ASSOCIATED WITH IT. SULLIVAN/PEREIRA GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 03/12Z 0.01 505673 500670 496669 490669 487671 483672 476678 467686 462690 458696 451707 448710 441716 430723 425724 419727 410739 403747 398757 393766 389776 381797 376808 370818 364827 358836 353843 346851 335867 328876 319886 306897 301900 298905 299911 297916 284927 276935 270944 265950 257956 243966 239969 238973 236977 237981 245989 252995 256997 261996 273996 277995 282996 283003 286009 290012 301011 314011 321010 328009 343998 350992 354984 363962 368953 375942 384924 388915 395904 399895 401885 403878 405873 411861 415852 421842 425832 428827 432823 450807 460798 470787 479778 482774 486768 492759 499748 501733 503727 504719 503711 502703 503698 505694 507688 506682 505673 0.01 521270 522261 521255 521250 520244 517236 513228 510222 506216 508211 512212 517216 522218 525217 529216 532213 534209 535196 535189 532180 528171 522164 512152 501141 491132 486126 483121 481108 479105 475104 460106 458107 455110 453111 449109 444105 438103 435104 432108 428114 424119 420125 415138 412145 412149 413153 414158 417161 420162 423166 424174 430177 436180 439185 440190 443194 449196 451198 453197 455193 459189 466187 473185 477191 478199 474203 468206 454212 442215 437219 435221 437225 441228 446228 433236 429241 425246 425251 426254 432258 439260 444261 461263 469266 476268 484272 489276 500289 504292 508293 512290 516283 0.01 453230 450229 448229 450230 453231 453230 0.01 446133 446129 446125 443124 440123 437124 434128 432132 431135 430136 430140 431140 433139 436140 439141 440141 442141 445137 445136 446133 0.01 412057 410049 408045 403036 397027 394025 388025 385029 383035 381039 378040 369036 360041 356044 353048 349049 344049 341049 340052 343055 349061 353063 356061 361058 364057 370057 373058 376061 374065 372068 374072 378074 381072 384068 387068 395067 402066 404064 407060 412057 0.01 268802 263798 259795 253795 250792 247793 243797 242804 242812 244817 248819 253820 256819 256816 255809 263807 268805 268802 0.25 489742 489736 487732 484728 480727 475728 472729 467733 460739 451749 445754 428755 420759 413767 405783 397801 388817 377833 367846 356860 345871 337879 332886 326891 318896 313901 312907 313912 313915 310918 304924 296931 290937 286943 284946 285949 292950 297948 300946 310943 313944 314947 314951 316958 317961 316964 313973 311977 308979 303985 299991 300996 304998 307997 315994 323989 329983 340972 352958 361946 366938 370928 377913 391881 402862 409846 415827 419809 423799 428788 433781 437777 442775 449776 457773 467767 475761 481756 486750 489742 0.25 515277 517272 517267 517259 514247 510236 505225 499215 497211 493207 488205 483205 476207 467213 464216 462220 464226 467226 471226 474224 481225 484228 491234 491239 490239 484239 476233 473236 470241 471246 477249 482253 485257 490266 496276 504283 507283 511281 515277 0.25 526198 525188 521181 516175 507171 502166 496158 493158 491164 491171 492180 497186 505191 511195 515197 519199 522200 524200 526198 0.25 474159 472154 468151 462151 459152 454155 451159 450163 452167 453172 453180 456182 457181 457177 457173 460171 463168 468166 472163 474159 0.50 513271 514263 514258 511251 508240 506234 496217 491213 487210 482209 475211 469217 469219 472221 478221 484223 492228 497234 501242 502246 502252 498254 494253 490252 490257 492264 497272 502277 508278 513271 0.50 413797 408799 403805 397814 389825 382835 365855 358863 349873 339883 333892 329896 329899 331900 334901 336903 332909 331915 326921 323924 318922 311922 306926 298934 295940 298943 304941 309938 318932 321931 324932 326938 322965 322973 319976 312984 310987 311989 315989 320986 324981 327976 343962 348956 353950 358942 369920 381896 392873 398860 402849 406837 410823 412815 413808 413797 1.00 396848 396843 394838 390839 381847 373855 367864 360874 354885 350896 348902 346906 340918 338922 336929 334940 333949 334953 337956 342952 347948 354939 365919 374898 380886 385876 390863 395853 396848 1.00 312931 310929 307930 305932 304933 303935 302937 303938 306937 308935 308934 311932 312931 1.50 384857 383856 380857 377859 371866 362880 359887 357890 357896 350912 344927 341934 340938 340942 345940 349938 351934 355928 360920 364913 367907 370898 374890 378883 381876 384857 2.00 369889 373881 375874 376870 373870 369878 367882 366886 366889 366890 369889 24HR QP VT 04/12Z 0.01 501672 498662 495652 491643 486636 479629 474628 468633 459646 455652 452658 446670 442677 438684 432695 422705 411713 407717 404723 404731 402737 396742 390745 379751 372753 365755 345762 333767 329770 326775 325780 326787 329791 333794 336798 335803 331808 322816 316825 320828 322830 319833 310838 306843 304848 304855 301858 293857 287859 283862 276871 276876 276884 277888 281890 283891 274908 272920 269933 267938 264941 257947 250953 247956 247964 249970 254970 265969 271967 278963 287959 296953 304948 322935 330930 340922 348915 358906 362903 366900 370895 376893 396879 400878 405879 410881 415885 425890 429892 435891 440889 445883 445878 438877 435877 429875 425872 423869 422864 421859 422855 424850 430839 435828 439822 442816 448813 452814 461811 462805 463796 466783 468776 471769 476756 482742 489728 495713 498703 501695 502686 501677 501672 0.01 549103 547098 543096 537087 526066 523059 521056 517053 514054 506063 500067 496068 491069 488073 482085 476094 470102 464099 461094 458083 456067 455059 456055 462044 467034 475030 478027 480020 478010 476006 469999 460992 454985 450982 447983 444987 444990 444999 443007 440012 434016 427018 422021 421024 421029 426033 432036 432040 430047 412053 407053 402056 399060 398068 398073 399077 404080 408081 411079 416076 419073 421070 424071 427075 428079 427083 424083 422087 424095 427100 426101 420107 417112 417120 419126 418135 418142 420142 422139 424131 425127 429123 432122 435123 440122 447125 452123 455118 458116 462114 467115 472117 478118 478122 475124 470126 466132 460137 457141 454147 453155 455160 462169 465174 471176 474176 478178 485185 492193 499195 502196 507201 520217 525219 531220 535218 537212 536205 538197 533185 530174 528168 525164 517157 512152 509147 534112 537108 541105 549103 0.01 521269 521261 520255 518250 515248 513242 512236 507228 504218 500209 493202 492199 489197 484198 481202 478204 469205 463210 460212 455212 452214 450219 450225 453229 452240 459246 466248 473252 482257 489264 499279 503284 507287 512288 516284 0.01 494235 492230 489229 487233 488234 491235 494235 0.01 255813 255810 254807 253804 251802 250802 248803 245804 244805 243807 243809 242812 242813 243815 243816 245817 247819 248819 250819 253819 254817 255816 255813 0.25 485665 484659 482654 479650 477650 472652 468656 460664 456671 449686 442697 436704 433710 427724 424731 420738 402758 396764 388769 384774 383780 380788 377793 366801 360806 356812 350822 339846 333857 330869 327876 330883 335895 338896 343895 350891 359884 378866 390858 402849 412838 415833 419827 425814 433802 438796 442790 448777 451769 454763 458757 462751 478723 481716 484707 485699 486690 486677 485665 0.25 506114 505112 504109 504104 503100 502098 500095 499095 497095 496095 494096 492099 491103 491108 491112 493117 494117 496118 499119 501118 502118 505114 506114 0.25 492221 490218 488215 487215 484217 483218 484218 487220 490221 492221 0.50 481674 479665 476662 472664 470666 467671 460682 452694 438715 434725 425737 412756 406764 398776 393784 389794 385799 379803 368810 362817 357826 351836 346845 345849 346857 348863 351866 354867 358866 364861 370854 378846 381842 386838 393835 397832 402829 408825 421809 429797 435787 440778 446767 453756 460745 471725 477712 480699 481692 482684 481674 1.00 470703 466702 462705 454715 442729 434737 428743 424747 422751 420759 418770 413777 411781 410786 410791 412793 417792 420789 427782 432775 438766 450752 454744 459735 462727 467716 469709 470703 1.00 362839 360838 358841 361841 362839 1.50 447738 445738 442739 439740 437742 434744 432747 431748 430751 430754 430758 431761 434761 436760 439757 441754 443751 445749 445748 447743 446742 447738 24HR QP VT 05/12Z 0.01 505647 501637 498630 489621 485618 481617 472621 466622 463625 460629 457632 454634 442641 432647 422652 411655 402658 393662 386665 379669 369676 357685 351693 350698 346704 337711 328718 320725 289758 283768 279776 275784 273787 269788 263788 258791 257797 259801 258803 254802 242809 239813 239818 243823 246826 253829 262830 267828 270824 273822 279820 286817 289814 289812 284801 291795 295790 302788 309792 312793 318790 322788 325790 325797 319807 313816 313822 316828 322824 325820 331812 339809 344808 349804 354801 358797 360797 364797 367795 379793 381793 380798 373808 366817 362826 359836 364839 368839 379831 392826 400827 406828 410827 417818 420814 422814 427815 432815 447808 450806 452802 455797 458790 460785 463773 470761 477750 482741 486735 489729 495718 498711 500702 503688 505682 504673 505657 505647 0.01 533215 534208 534200 532191 529184 524177 520174 516173 509175 505175 502178 502184 503188 508195 510198 513204 515210 520219 525222 530219 533215 0.01 514281 516273 517266 516253 513244 509231 506225 499218 490211 483207 478206 473203 468203 465206 463211 465215 475219 478219 480220 484222 486227 489229 491234 490235 487241 483245 481246 478249 476256 475264 477275 482284 488290 491293 493294 499294 502295 506293 509291 512285 514281 0.01 524928 524921 524917 522914 521910 518906 509898 505897 503897 494900 490900 486899 478897 471895 465893 456885 451881 445878 437877 429877 414879 407883 400885 392888 385891 382894 380897 377905 377910 380915 383918 391918 393919 394924 394943 396956 398964 400968 402974 403985 401990 402995 404999 408997 413998 413002 413010 409019 407021 407026 410034 412037 413041 413051 416059 420065 427069 430073 431076 436081 444082 450087 455090 457089 459085 461076 465073 470074 474074 476072 477066 476061 472055 467051 462046 456043 453040 452036 449027 448020 449018 453016 456018 459026 462027 464025 473015 480011 488006 495003 501004 509007 513006 518001 521993 522986 522979 521971 519963 515955 514947 515940 519935 524928 0.01 436992 437988 435985 432985 429986 427989 426989 424993 427997 429997 430996 433995 436993 436992 0.25 496650 493640 489636 481631 477631 471634 464639 458645 442666 434676 428680 424682 417684 413685 405683 400683 394685 389686 384689 378693 373698 366705 361710 358714 350723 342731 336740 336744 336747 339750 349748 359743 367737 377728 387719 395711 405704 411701 415700 420702 421706 425709 429709 432712 440718 444721 445725 445729 439741 437746 438750 440752 446745 449741 453734 455728 459722 462718 466715 476710 482705 485700 490686 493677 495667 496658 496650 0.25 454935 452927 448920 441913 435912 432914 431920 435930 435932 433934 429941 428947 429953 432956 435956 444955 449951 452944 451939 454935 0.50 490650 488644 485640 479637 473641 466646 462651 455660 444675 440681 438685 437690 439695 444700 451703 457703 470699 477697 482693 487685 489676 490666 490655 490650 $$