FXUS04 KWBC 010725 PAA QPFPFD QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 324 AM EDT WED SEP 01 2004 PRELIM DAY 1 AND DAY 2 QPF DISCUSSION VALID SEP 02/1200 UTC THRU SEP 03/1200 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR ...PRELIM DAY 1... ...SYNOPSIS... A RIBBON OF FAST WRLYS WL EXIST ALNG THE U.S./CAN BORDER WITH A SHARPENG UPR TROF OVR SWRN CAN INTO THE PAC NW/NRN ROCKIES...WHILE A BROAD/FLAT TROF PROGRESSES ACRS THE NERN U.S./ST LWRNC VLY REGION. A BROAD MID/UPR LVL RDG WL REMAIN IN PLC ACRS THE SRN 2/3RDS OF THE CONUS...BUT THE MDLS SUPPORT WEAKENG THE RDG OVR THE SCNTRL U.S. BY THU MRNG. AT THE SFC BNDRY DRAPED ACRS THE SERN U.S. WL MOV VRY SLOLY TO THE SE THIS PD AND BE A FOCUS FOR CNVCTN. ANOTHER WEAK BNDRY INITIALLY ACRS THE NRN TIER STS WL WEAKEN AND LIFT INTO CAN...WHILE A MOD CDFNT MOVS THRU THE NWRN U.S. ...SERN U.S... THE SFC BNDRY DRAPED ACRS THE REGION WL BE THE MAIN FOCUS FOR CNVCTN THIS PD...BUT THE DEEP MSTR IN PLC COULD SUPPORT CNVCTN JUST ABT ANYWHERE OVR THE SERN U.S.. MDLS ARE POINTG AT A FEW PLCS WHERE LOLVL FOCUSG WL BE STGR AND MIDLVL SUPPORT WL EXIST. THE FIRST IS OVR NC/SC WHERE MSTR IS VRY DEEP. 01/00 UTC PW ANLYS SHOWED 2.30 INCH VALUES ALNG THE CST. WV IMAGERY ALNG WITH MDL SUPPORT SHOWS A WEAK VORT LIFTG SLOLY NEWD TDA THAT WL PROVIDE SOME UPR SUPPORT. THE FLOW REMAINS DIFL AS A WEAK UPR RDG IS PSTND TO THE S. MDL SOUNDGS...S OF THE RNFL AREAS...SHOW CAPES BLDG TO ARND 1500 J/KG. SOUNDGS ALSO SHOW AN EXTREMELY MOIST AIRMASS WITH WBZ LVLS NR 4KM. VRY EFFICIENT RNFL PRDCRS ARE LKLY TDA. THE GFS IS SHOWG SIGNS OF FEEDBACK AS IT GENERATES A VRY STG AREA OF 8H CVRG AND 7+ INCHES OF RN. THERE IS NO STG 5H VORT...THAT USUALLY SHOWS UP IN THESE SITUATIONS. THE GFS IS MORE CONSISTENT WITH HVY RNFL ACRS NC...WHILE THE ETA IS TRENDG NWWD TWD THE GFS SOLU. ALTHOU ALL SIGNS POINT TWD GFS FEEDBACK...THERE IS SUPPORT FOR SOME VRY HVY RNS OVR A SMALL AREA. XPCT SOME TWO INCH PER HR RNFL RATES WITH ISOLD HVIER TOTALS BY THU MRNG. A SCND AREA IS OVR THE SRN APCLHS WHERE ANOTHER SHRTWV IS XPCD TO MOV ACRS THE REGION. MDLS ALSO SHOW SOME 8H CVRG AND THETA-E ADV ACRS THE HIER TERRAIN. THE ERLY FLOW SHLD SUPPORT OROGRAPHIC LIFT. XPCT MOSTLY LATE MRNG INTO ERLY EVE CNVCTN THRU THE REGION WITH ISOLD 1-2 INCH AMTS PSBL. THE THIRD AREA SHLD BE THE FL PENINSULA WHERE ERLY LOLVL FLOW WL SUPPORT RW DVLPG ALNG THE ECST THIS MRNG AND WRKG WWD THIS AFTN. XPCT ANOTHER WCST/ECST SEA BREEZE COLLISION THIS AFTN THAT WL SUPPORT A BRIEF PD OF VRY HVY RNS. LCL 1-2 INCH AMTS ARE PSBL. ...SRN ROCKIES INTO THE UPR RIO GRANDE VLY... MDLS ARE VRY CONSISTENT WITH KEEPG A PLUME OF DEEP MSTR FEEDG NWWD UP THE RIO GRADE THIS PD. PWS FM THE LWR RIO GRANDE INTO THE BIG BEND AREA SHLD BE AOA 1.50 INCHES. MIDLVL SUPPORT WL BE PRESENT AS A VORT IS ALRDY IN PLC AND XPCD TO MOV VRY SLOLY SEWD AS IT IS CAUGHT IN THE BROAD UPR RDG ACRS THE REGION. CNVCTN WAS NOT A WDSPRD TUE AS PRVS DAYS...SO THINK THERE SHLD BE MORE HEATG TDA ACRS THE REGION WHICH SHLD SUPPORT A LITTLE MORE INSTBLTY/CAPE. THE PERSISTENT LOLVL SERLY FLOW WL SUPPORT UPSLOPE ACRS THE HIER TERRAIN. XPCT CNVCTN TO FORM THIS AFTN OVR THE HIER TERRAIN AND WORK SLOLY SEWD WITH ISOLD 1-2 INCH RNS IN A FEW SPOTS. ...UPR MS VLY/WRN GRT LKS... A RETREATG FNTL BNDRY WL SUPPORT VRY WEAK THETA-E ADV ACRS THE REGION. INSTBLTY/MSTR WL BUILD S OF THE BNDRY...BUT THE LOLVL FOCUS WL REMAIN WEAK. SO ONLY XPCT SCT CNVCTN ACRS THE REGION WITH LGT RNFL AMTS. ...NWRN U.S.... THE STG MIDLVL SHRTWV TROF CROSSG THE REGION WL BRING SGNFCNT HGT FALLS AND A MOD CDFNT THRU THE REGION. MSTR IS NOT VRY IMPRSV...BUT MDLS SHOW INCRSG UPR JET DYNAMICS...SOME UPSLOPE AND 8H/7H CVRG AS THE SHRTWV ENERGY APRCHES. THIS SHLD WRING OUT THE AVBL MSTR WITH SOME LGT/MOD RNFL AMTS IN THE FAVORED HIER TERRAIN. MDLS ALSO SHOW INCRSG INSTBLTY LATER TDA/THIS EVE AS THE MIDLVL COLD POOL SLIDES OVR THE REGION. DAY 2... ...MID ATL... THE TAIL END OF AN OLD LOW LVL BNDRY AND A COINCIDING PLUME OF DEEP MOISTURE WILL LINGER ALONG THE NC COAST THIS PERIOD. IN ADDITION TO THE AMPLE MOISTURE SUPPLY...A WEAK VORT LIFTING TO THE N ACROSS THE AREA AND DIFFLUENT FLOW ALOFT WILL LEAVE THIS AREA PRONE TO SIGNIFICANT RAINS THIS PERIOD. AS INDICATED IN THE DAY ONE DISCUSSION...THE GFS APPEARS TO BE SUFFERING FROM FEEDBACK PROBLEMS AS IT GENERATES A VERY STRONG AREA OF 8H CONVERGENCE THAT IT LIFTS NWWD INTO SRN VA PERIOD AFTER INUNDATING THE OUTER BANKS WITH 5+ INCHES. THE ETA...ALONG WITH THE UKMET/CAN GLOBAL...IS MUCH MORE SUBDUED AND KEEPS THE BULK OF ITS PCPN ALONG WITH THE 8H BNDRY OFFSHORE. THE GFS HAS BEEN FAIRLY CONSISTENT THOUGH AND THE ETA HAS BEEN SHOWING A NWD TREND WITH THE BNDRY. THEREFORE...WHILE NOT GOING NEARLY AS FAR N OR AS HVY AS THE GFS...DID BRING THE AXIS OF HEAVIEST PCPN FURTHER N THAN THE ETA. ...NRN ROCKIES TO THE NRN PLAINS... BOTH THE ETA/GFS HAVE TRENDED WEAKER/MORE SLY WITH THE UPR LOW MOVING OUT OF CANADIAN ROCKIES AND ARE DEEPER/LESS PROGRESSIVE WITH THE ASSOCIATED TROF STRETCHING BACK ACROSS THE WRN U.S. THE ETA FITS THE TREND BEST...BOTH ALOFT AND WITH A SLOWER/STRONGER SFC FRONT AS WELL. HOWEVER...A DRAMATIC CHANGE IN BOTH MODELS OVER THE PAST 12 HRS WITH THESE FEATURES AND THE UPSTREAM TROF OVER ERN CAN GIVES RISE TO UNCERTAINTY. THEREFORE...OPTED FOR A MODEL BLEND HERE. DID GO CLOSER TO THE ETA AMTS THOUGH. GIVEN A MOIST SLY INFLOW OF 50 KTS AT 8H AND GOOD UPR LVL DIVERGENCE...FELT THE GFS WAS TOO DRY ACROSS THE NRN PLAINS. ECKERT/PEREIRA GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 02/12Z 0.01 535216 537208 539201 539192 538187 537180 534174 530165 520149 510135 508131 504123 505112 509101 515095 520091 522084 521077 519072 514064 511062 507061 497062 489065 477077 473081 469084 467087 464093 464096 461101 459101 456099 453096 448094 444094 438094 435096 433096 430098 429102 426105 424108 426111 429116 431118 436117 440119 446123 452130 454135 454139 450139 447142 438143 434147 433154 443168 446175 445178 441181 439186 438193 441204 465181 474182 477183 479185 481188 482193 481199 478203 475203 445216 442218 440223 444227 449228 453226 456227 453231 445233 439236 435238 430240 428244 432246 439244 446244 457245 465247 476251 481253 483255 488261 492266 498268 502267 502262 499254 496249 493241 489237 487235 484234 483234 482231 481229 478228 477228 475229 473227 476222 480223 485227 490231 495238 499246 508255 512256 515253 515240 515229 516225 520221 523221 530222 535216 0.01 446966 463974 481982 496990 507990 515977 509963 494946 483934 470922 462917 457913 451902 449888 451873 454866 454860 453853 449843 446837 443836 438838 436840 435850 435863 431872 427879 423887 420895 418907 417916 417922 417929 419936 421940 427948 432955 437960 445966 446966 0.01 429187 430183 429183 426185 425186 426188 429188 429187 0.01 431168 431167 428166 427167 428171 431171 431168 0.01 425131 426127 427123 426121 423123 423124 420127 419129 419130 419134 422135 425132 425131 0.01 421158 421154 421150 421149 418146 415146 415149 414153 414157 414161 417162 419161 420160 421158 0.01 368749 366740 361733 356733 353735 347737 340742 337747 332761 324787 320800 314812 312816 308817 303814 299809 292805 283800 277797 271796 265796 258797 250800 246806 245809 246815 250822 259830 268835 281838 286841 288845 289850 292855 291861 291867 294872 299875 300878 299881 298888 295893 292898 290907 291921 295921 297918 301913 307906 311902 315896 317891 321886 329886 336887 342889 347888 351882 354874 356867 360856 363850 367843 372837 376830 379825 381821 381816 379812 377810 373809 371809 367809 362811 359811 357809 356801 357793 358785 360776 362771 365762 368753 368749 0.01 410152 410149 410146 407148 403151 401155 403159 406157 407156 409153 410152 0.01 383035 383029 381028 376028 372029 355036 348038 342039 337038 333038 330035 324029 318024 319011 318005 315001 312999 307998 298999 290998 276991 269988 261986 258984 252983 246987 244991 244997 250003 262014 271025 276032 280038 284045 289051 300062 306066 314071 320071 324068 327065 330065 340065 348067 352065 355061 361058 366056 371056 376056 381055 382048 381041 383035 0.01 337095 336092 335089 333086 330085 327088 327089 328092 330094 331095 332096 335097 337095 0.25 531199 533187 533181 532178 528170 523163 518159 513155 500149 495143 492135 491131 489126 486124 483123 480124 478125 475126 473131 474139 477140 484142 486143 490147 493151 496154 498157 497159 493159 490159 485161 483164 483169 485175 488177 489179 494185 497193 497199 494201 489205 478210 475211 476215 481217 483218 485218 487220 488219 490219 491222 493228 495231 497236 500238 503235 503228 502222 502218 501212 500208 501205 502201 505201 508201 513204 519208 524208 526207 529204 531200 531199 0.25 492250 489241 486242 488249 492250 0.25 477234 475233 473234 473238 475240 478242 479242 480239 478235 477234 0.25 363756 363751 361747 359745 356745 351745 346750 342755 339760 334771 331780 327793 325798 325804 327807 329808 336805 343802 346798 350792 352787 355775 359764 363756 0.25 366830 366827 365823 363821 359820 354821 352824 350825 347830 343834 340835 336838 333841 331843 329848 325851 318855 312858 307859 305863 310865 320862 329861 337861 340863 345864 351859 355851 359842 364835 366830 0.25 319834 317831 314829 307828 296820 290814 285811 278807 271804 264803 257805 252810 251814 252816 257822 262826 275831 281833 289835 296836 298840 297843 298848 300849 310846 316842 318838 319834 0.25 336051 335048 333048 327045 324042 321038 318034 312033 310031 307027 306023 306017 305011 300008 291006 275002 266001 265005 267009 273014 280019 283022 285025 287028 288034 293043 299049 305054 313052 321053 324055 327059 330058 333056 336051 0.50 526198 525193 527188 528184 528179 525173 522171 516171 510167 504167 501171 500172 499177 503182 506186 508189 514193 516196 522201 526198 0.50 360757 361753 360750 356748 351749 346753 341760 337770 334778 331787 331791 333797 342794 347791 349788 352780 355769 358761 360757 0.50 353845 355842 357838 359834 357831 355830 354827 352828 349832 346838 344842 343847 343850 344853 349853 352850 353845 0.50 296826 291822 287817 283813 278811 272808 270807 265806 261807 257808 255811 257817 260821 266824 271826 276829 282831 288831 292831 296828 296826 0.50 310042 309039 307037 305036 304035 301033 300033 298033 297037 297040 299041 300043 302044 304045 307044 310042 0.50 303020 303017 301014 297012 292012 289011 286008 282006 278006 273007 275010 278013 283016 287018 289019 293024 295026 300024 303020 1.00 358755 355751 349753 346758 343762 341768 339777 339782 340786 343788 346787 350783 352773 354767 355763 357759 358755 2.00 349773 352765 353757 351757 349759 347761 346764 344769 344774 345777 349773 24HR QP VT 03/12Z 0.01 523258 515254 512251 511244 511241 509236 507229 500209 496203 495201 494202 492203 488204 483202 478202 475203 464208 449212 438218 449233 444236 441239 440244 447246 453245 469247 477250 481252 485252 488252 490247 490243 486241 481240 477234 470231 468231 468227 470225 476222 483224 488224 492228 495231 497236 498241 498245 500251 499260 496260 495262 494268 494272 497277 501282 511292 0.01 542197 539186 537178 536172 536163 534157 527149 521143 513137 508135 503135 495135 488128 480123 474124 470127 468128 469121 473112 478103 482098 488093 501078 507069 509063 509056 507052 502051 497052 492053 486059 482065 479068 475071 473072 470070 470063 472057 478049 499018 501014 506013 514009 520006 523003 525997 527992 527977 525969 523964 518958 511956 501956 495957 490958 484959 479962 475964 471968 460980 453986 448994 439011 428027 424037 421045 413060 406077 404083 403089 400094 396096 392099 391103 391109 388112 385116 385120 391121 401121 406125 408129 412132 418133 424134 428131 434128 438128 441131 457139 459143 459146 460154 462159 465165 468168 473171 476173 483182 487190 493197 496199 498204 510207 516219 520223 525224 529222 534224 0.01 369721 367714 364709 361704 358703 355706 354710 353716 350717 342718 338724 332739 329747 325754 315770 305782 299788 292795 286794 278795 272797 268796 261795 256795 251797 246803 241816 242823 250823 259825 267828 273831 278834 284841 287846 290857 290867 288876 285886 281892 276897 266907 263914 262919 265922 273925 281925 287924 293925 296933 298935 303935 307930 317927 323922 331915 334913 336914 339916 342918 346917 352911 357905 362902 366902 371902 376901 382899 387895 390892 393888 396884 397879 399868 399861 397854 393850 391849 387848 384846 380844 377844 368844 361840 357827 355823 352822 347824 343826 340824 338822 336817 335810 336805 341803 346801 351798 354794 359792 362787 366784 371776 374767 375757 374750 371732 369721 0.01 311039 312035 312031 309024 307019 303016 298013 294009 288003 281993 276982 270973 263967 253962 246962 241966 239971 236981 236989 239996 243004 250013 257021 264027 273032 283037 293040 299040 305041 308043 311039 0.25 534205 533199 532194 529186 530179 530174 529169 526164 520154 514153 512150 506147 503147 500150 499157 496160 493164 491171 493176 498179 503188 514194 520201 522204 525206 530208 534205 0.25 470012 469012 466012 463013 466013 469013 470012 0.25 462110 463106 462101 460097 456093 453088 450078 447072 444070 440072 441076 446078 449084 444088 438086 430089 427092 427096 426100 423104 421111 422115 423117 426118 429117 435112 443116 446121 449123 456118 460114 462110