FXUS04 KWBC 271010 PAA QPFPFD QUANTITATIVE PRECIPITATION FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 610 AM EDT SUN APR 27 2003 FINAL DAY 1...DAY 2 AND DAY 3 QPF DISCUSSION VALID APR 28/1200 UTC THRU APR 30/1200 UTC REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR ...UPDATE DAY 1... CHNGS IN THE 06 UTC ETA/GFS ARE SUBTLE. THE STG CLSD LOW MOVG TWD CA IS NOW STGR IN THE ETA...WITH HVIER PCPN AMTS. THE ETA/GFS ARE BOTH SHOWG MORE PCPN INTO THE WRM SECTOR LATER TNGT THRU THE CNTRL PLNS. THE GFS HAS SGNFCNTLY REDUCED PCPN ACRS THE FL KEYS...WHILE THE ETA HAS INCRSD AMTS IN SRN FL. WITH ALL THIS...DON'T REALLY SEE ANY REASON TO MAKE ANY DRASTIC CHNGS TO THE PRELIM DAY 1. DAY 1... ...FL... THE LATEST SFC ANLYS SHOWS THE MCS RACG SEWD AND WEAKENG AS IT PLOWS INTO CUBA ERLY THIS MRNG. THE MESO-HI HAS PASSED THE KEYS WITH SRLY FLOW RETURNG ACRS SRN FL. THE MAIN SYNOPTIC BNDRY WL LIE ACRS CNTRL FL TDA WITH THE ATMOS ACRS SRN FL XPCD TO SLOLY RECOVER AND BCM SOMEWHAT UNSTBL LATER THIS AFTN/EVE. ENUF MSTR...INSTBLTY AND SBTRPCL JET STREAM ENERGY SHLD SUPPORT ANOTHER ROUND OF CNVCTN THAT SHLD MOV SEWD ACRS THE REGION THIS AFTN/EVE. WV IMAGERY DOES SHOW A JET STREAK MOVG FM SRN TX INTO THE CNTRL GULF THIS MRNG THAT WL MOV OVR THE FL STRAITS LATER TDA. THIS SHLD HELP INCRS THE UPR DVRG. THE GFS IS HAVG GRIDSCALE FEEDBACK TRBL AND THIS LEADS TO NRLY SEVEN INCHES OF RN NR MTH THIS AFTN. DON'T HAV A LOT OF CONFIDENCE IN THIS SCENARIO...BUT ISOLD ONE INCH RNS ARE NOT OUT OF THE QUESTION. ...CNTRL PLNS/LWR MO VLY... THE MDLS ARE IN GD AGREEMENT WITH BRINGG A SERIES OF VORTS FM THE SRN ROCKIES INTO THE PLNS AND FORMG ONE MAIN VORT THAT MOVS ACRS THE REGION TNGT. THIS WL SUPPORT THE SEWD PUSH OF A WEAK CDFNT INTO THE CNTRL PLNS THAT SHLD BCM THE FOCUS FOR CNVCTN LATER THIS AFTN/EVE ACRS SERN NEB. MSTR WL INCRS THRU THE REGION IN RESPONSE TO INCRSG SRLY FLOW WITH THE MDLS SHOWG PWS BUILDG TO NR 1.25 INCHES. 8H DWPTS ARE XPCD TO INCRS TO THE LWR TEENS AND BCM ANCHORED IN A ZONE FM SRN KS INTO MO AND NRN IL BY ERLY MON MRNG. BOTH THE ETA AND GFS SHOW AN 8H THETA-E RDG BUILDG THRU SRN KS INTO MO LATER TNGT WITH THE LLJ INCRSG TO 30-40 KTS. AT THE SAME TIME THE MDLS SHOW THE MAIN INSTBLTY AXIS LYG ACRS THIS SAME AREA WITH LITTLE IN THE WAY OF A CAP. THEREFORE...THINK THE INITIAL CNVCTN WL FIRE OVR SERN NEB AND MOV NEWD...WHILE BUILDG SWWD INTO THE INCRSG UNSTBL AND MSTR RICH AIRMASS OVR THE CNTRL PLNS. MDL QPFS ARE LGT THRU THIS REGION...BUT THE MASS AND LOLVL THERMAL FIELDS ARE POINTG TWD CNVCTN DVLPG MUCH FARTHER TO THE SW THAN INDICATED IN THE MDLS. AT THIS TIME...DON'T THINK THERE WL BE A HVY RN THREAT DUE TO TO THE LACK OF DEEP MSTR THRU THE REGION. ISOLD ONE INCH RNS ARE PSBL. ...SWRN TX... THE DRYLN WL REMAIN IN PLC THRU THE PD WITH SOME LOLVL MSTR XPCD TO BUILD ALNG THE BNDRY AS PERSISTENT SRLY FLOW BRINGS GULF MSTR NWD. MDL SOUNDGS ARE NOT VRY IMPRSV WITH THE MSTR...BUT THERE WL BE INCRS MID/UPR LVL LIFT THRU THE REGION AS SBTRPCL SHRTWV ENERGY PUSHES INTO THE REGION THIS EVE/TNGT. THE LATEST WV IMAGERY SHOWS ONE SHRTWV MOVG INTO NRN BAJA THIS MRNG WITH A DECENT UPSTREAM SHRTWV RDG. THE ETA/GFS BOTH SHOW INCRSG UPR DIFL FLOW BY THIS EVE WITH SVRL PIECES OF MIDLVL VORT ENERGY PUSHG INTO THE REGION. XPCT WDLY SCT CNVCTN TO FORM ERLY TNGT AS THE MIDLVL ENERGY PUSHES INTO THE REGION. OVRALL QPF AMTS WL REMAIN RATHER LGT. ...NRN GRT BASIN TO CNTRL ROCKIES... A STREAM OF MID/UPR LVL PAC MSTR WL CONT TO SUPPORT LGT PCPN THRU THE REGION TDA. ...CA... A STG VORT DIGG SEWD TWD THE NRN CA CST WL BRING DECENT HGT FALLS AND INCRSD UPR LVL DIFL/DVRG TO THE REGION. THE MDLS ARE DIFFERENT IN THAT THE GFS IS MUCH DEEPER WITH THE 5H SYS AND THE GFS IS WETTER THAN THE ETA. THE LATEST WV SATL PICS SUPPORT A VRY STG SYS WITH MIDLVL ENERGY CONTG TO DIG INTO THE BASE OF THE SYS THAT SUPPORTS THE STG GFS. BOTH MDLS ARE SIMILAR IN THE MDLG OF THE LOLVL MSTR PLUME AND LOLVL ONSHORE FLOW...BUT THE ETA CONTS TO SHOW A BIAS OF FCSTG TOO LITTLE PCPN WHERE THE MSTR PLUME/INFLOW AXIS INTERSECTS THE MTNS. THE GFS HAS HVIER PCPN...BUT PLCS THE PCPN IN THE VLY INSTEAD OF ALNG THE FAVORED WRN SLOPES. SO HAV ACCEPTED THE GFS HVIER PCPN...BUT ADJUSTED FOR THE TERRAIN AND INCRSD IN THE NRML UPSLOPE REGIONS. ...U.S./CAN BORDER REGION... MIDLVL ENERGY OVR ERN MT ERLY THIS MRNG IS XPCD TO CONT RACG EWD AND SHEAR APART AS IT GETS CAUGHT UP IN THE FLOW ARND THE SRN EDGE OF THE DEEP HUDSON BAY UPR LOW. MSTR FEEDG INTO THE REGION IS MARGINAL...BUT IT WL TEND TO POOL ALNG THE BAROCLINIC ZONE THAT'L LIE ALNG THE U.S./CAN BORDER. THE MIDLVL FLOW IS RATHER FAST...SO THE PCPN WL MOV QUICKLY AND THEREBY LIMIT QPF AMTS. ...ME... LINGERG LGT PCPN ERLY THIS PD WL EXIT THE ST BY THIS AFTN AS THE MIDLVL SHRTWV TROF LIFTS INTO ERN CAN. DAY 2... IN THE DAY 2 FCST... THE CLOSED UPPER LOW OFF THE NRN CA COAST AND ASSOCIATED UPPER-LEVEL DYNAMICS DRIFT EASTWARD INTO THE INTER-MOUNTAIN WEST... THE ACTIVE SUBTROPICAL JET WILL ALLOW A FEW SHORT WAVES TO DEVELOP IN THE BROAD SWRLY FLOW IN THE PLAINS... A POLAR FRONT WILL RAPIDLY MOVES ACROSS THE GT LAKES INTO NEW ENGLAND AND STALL ACROSS THE CENTRAL PLAINS AND LL ERLY FLOW WILL HELP TRIGGER SEA BREEZE PRECIP OVER FL. THE 00Z MODEL GUIDANCE OFFER NO CONSENSUS ACROSS THE CONUS DURING THE FCST LEAVING A VARIETY OF SOLUTIONS FROM THE WEST INTO THE ERN US. AS A RESULT... MANUAL QPF HAS A VERY LOW CONFIDENCE IN THE DAY 2 QPF. IN THE WRN US... THE ETA AND GFS ARE QUITE SIMILAR AT THE BEGINNING OF THE PERIOD WITH A VERY STRONG CLOSED 500 MB LOW ALONG THE NRN CA COAST. THE GFS HOLDS ONTO THIS STRONG CLOSED UPPER LOW LONGER THAN THE ETA AND MOVES THE SYSTEM INTO SWRN OR ALONG WITH ANOTHER SHORT WAVE INTO WRN NV. THE ETA BREAKS DOWN THIS CLOSED FEATURE INTO MORE OF AN OPEN WAVE WITH VORTICITY STRETCHING... BY THE END OF DAY 2... FROM THE OR COAST INTO ERN NV. THE ETA MODEL AS A RESULT IS SLIGHTLY FASTER THAN THE GFS BUT THE QPF FIELDS ARE RATHER SIMILAR. AS A RESULT... MANUAL QPF WENT WITH A BLEND OF THE ETA/GFS PRECIP FIELDS ON DAY 2 AND A PRECIP MAX OVER NRN CA... COASTAL RANGES AND INTERIOR HIGHER TERRAIN... AND SPREADING INTO THE SIERRA. ACROSS THE PLAINS... A VIGOROUS SUBTROPICAL SHORT WAVE WILL MOVE INTO THE VERY DIFFLUENT SWRLY UPPER FLOW AND THE POLAR COLD/STATIONARY FRONT STRETCHED ACROSS THE CENTRAL PLAINS EARLY IN THE PERIOD WILL BEGIN TO LIFT NORTHWARD AS A WARM FRONT. THE ETA AND GFS ARE QUITE DIFFERENT IN THE HANDLING OF EACH SYSTEM LEADING TO CLASHING PRECIP FIELDS. THE ETA IS MUCH MORE DEEPER AND STRONGER WITH THE SUBTROPICAL SHORT WAVE MOVING ACROSS TX/OK THAN THE SIGNIFICANTLY WEAKER GFS. THE CANADIAN AND UKMET ARE BASICALLY A COMPROMISE OF THE STRONGER ETA AND WEAKER GFS. A SURFACE DRYLINE WILL SETUP ACROSS WRN TX AND THE UPPER DYNAMICS FROM THE SHORT WAVE WILL HELP TRIGGER CONVECTION ACROSS THE EXTREMELY MOIST AIR MASS ACROSS WEST CENTRAL TX. MANUAL QPF LEANED TOWARDS THE MORE ACTIVE/AGGRESSIVE ETA PRECIP SOLUTION EARLY AND TRENDED TOWARDS A COMPROMISE LATER IN THE FCST. THE ETA ALSO HAS A STRONGER SHORT WAVE EJECTING OUT INTO THE CENTRAL PLAINS DURING THE DAY 2 FCST THAN THE GFS. THE COMBINATION OF THIS SHORT WAVE ALONG WITH MOISTURE OVERRUNNING THE FRONTAL ZONE AND AN ERLY LL COMPONENT WILL LEAD TO LIGHT TO MDT PRECIP FROM ERN WY INTO ERN KS. MANUAL QPF WENT WITH A COMPROMISE OF THE ETA/GFS QPF FIELDS HERE. THE FAST ZONAL FLOW ALONG THE NRN TIER OF THE COUNTRY WILL DRIVE THE NRN EDGE OF THE POLAR FRONT AND SURFACE LOW FROM THE UPPER GT LAKES INTO NRN NEW ENGLAND... THE FRONT STRETCHING BACK THROUGH THE NRN MID-ATL AND INTO THE OH VLY. PRECIP ALONG THE FRONT SHOULD BE VERY LIGHT WITH CONVECTION ACROSS THE SRN PLAINS/TX ROBBING AMPLE LL MOISTURE TO STREAK OUT AHEAD AND POOL. A WEAK SHORT WAVE THOUGH OUT AHEAD OF THIS FRONT WILL HELP PROVIDE A BETTER CHANCE FOR MDT PRECIP FROM MO INTO IL EARLY ON DAY 2. ANOTHER COMPROMISE BETWEEN THE GFS/ETA QPF FIELDS WAS USED HERE. FINALLY ON DAY 2... LL ERLY FLOW... PWS AOA 1.25 INCHES AND DAYTIME HEATING WILL LEAD TO SCATTERED CONVECTION ACROSS THE FL PENINSULA. MANUAL QPF FOLLOWED THE WETTER ETA ACROSS FL. DAY 3... NOT ONLY ARE THE SHORT WAVE DETAILS DIFFERENT ON DAY 3 BETWEEN THE ETA AND GFS BUT SO IS THE ENTIRE SYNOPTIC/LARGE SCALE PATTERN FROM THE ERN PAC INTO THE PLAINS. AS A RESULT... THE ETA AND GFS QPF FIELDS ARE DIFFERENT LEADING TOWARDS ANOTHER LOW CONFIDENCE FCST. THE UNSETTLED WEATHER WILL LINGER ACROSS THE PAC NW AND INTERIOR WEST AS THE CLOSED 500 MB VORTEX STRETCHES FROM THE ERN PAC INTO THE INTER-MOUNTAIN WEST. THE OLD CLOSED LOW ON DAY 2 DRIFTS NORTHWARD AND WEAKENS OVER OR AND INTO SRN WA. SHORT WAVE ENERGY WILL PASS THROUGH THE INTER-MOUNTAIN WEST AND BEGIN TO EJECT OUT INTO THE CENTRAL/NRN PLAINS BY 84 HRS. MEANWHILE... THE ASSOCIATED SURFACE LOW WILL MOVE INTO NWRN/NRN KS AND THE POLAR BOUNDARY WILL CONTINUE PROPAGATING NORTHWARD AS A WARM FRONT THROUGH THE PLAINS... MOST LIKELY THE KEY FOCUSING MECHANISM FOR A HEAVY RAIN EVENT FROM ERN MT/WY INTO IA/IL AND MN. A STRONG 850 MB JET WILL PUMP MOISTURE NORTHWARD AND OVERRUN THIS FRONT. THE TIMING AND LOCATION OF INDIVIDUAL SHORT WAVES AHEAD OF THE MAIN UPPER TROUGH EARLY ON DAY 3 WILL BE CRUCIAL TO THE PRECIP FCST. THE ETA AND GFS ARE DRASTICALLY DIFFERENT WITH SHORT WAVE INCONSISTENCIES FROM THE DEEP SOUTH ALL THE WAY TO THE NRN PLAINS. DUE TO THE SHORT WAVE UNCERTAINTIES... MANUAL QPF WENT WITH A COMPROMISE OF THE ETA/GFS PRECIP IN THE PLAINS... GOING WITH A 1 INCH MAX FROM THE CENTRAL SD/NE BORDER EWRD INTO SWRN MN/WRN IA. MANUAL QPF CONTINUED THE TREND OF CARRYING A STRONGER MID-LEVEL SHORT WAVE ACROSS THE DEEP SOUTH LEADING TOWARDS MORE CONCENTRATED PRECIP ACROSS ERN TX/LA OR A SLIGHTLY WEAKER ETA SOLUTION. ESERLY FLOW WILL LEAD TO MORE SCATTERED DIURNAL CONVECTION ACROSS THE FL PENINSULA ON DAY 3. ECKERT/MUSHER GRAPHICS AVAILABLE ON THE WEB AT WWW.HPC.NCEP.NOAA.GOV 24HR QP VT 28/12Z 0.01 481664 480658 479653 473647 465643 453640 448640 443641 437647 431653 430659 432667 436675 440682 445686 449688 459687 464687 467685 471683 475679 479671 481664 0.01 546168 547157 548147 546130 543117 539104 537088 535074 534066 533053 530039 526003 524983 524964 516892 514872 513856 510840 506821 498785 494769 492754 489736 486722 483714 481711 477707 473704 460748 457761 457774 455784 452797 450807 449821 449830 449834 450848 453864 454880 453908 455923 453938 449948 446952 447955 471951 479954 486961 502013 505018 507028 508044 509059 507075 507094 508107 508128 504128 501126 498121 499117 495113 493112 490113 487110 483109 480110 478112 481121 483126 484132 483139 483143 484148 485161 486170 487176 490182 492186 497189 500184 502175 504172 506172 510179 513183 518186 522190 536205 539207 540205 541198 541190 546168 0.01 524256 520247 517238 514226 510217 508212 505208 498203 493199 488200 485201 483206 480209 475210 473211 467212 464214 463217 467219 472219 487218 491220 493225 496236 498245 492245 489247 489250 490257 493261 498269 503271 507265 509270 514280 517280 0.01 463178 463173 460167 460164 464162 465157 462154 454149 445146 439143 437128 434123 437118 439116 443117 446121 448123 453124 456121 455117 457107 455097 451093 446093 444092 439088 438085 438079 441075 445075 451080 453081 452077 447072 441067 435057 433052 437048 436044 432035 426026 421020 418016 415008 413998 413988 414977 417964 421949 429930 434908 436895 438886 438877 436869 433865 430866 426873 422880 417888 412894 402898 395899 384906 379913 375925 370940 367951 366966 366978 368984 373986 378982 381975 383971 387971 389974 391981 393990 396998 400001 403004 403007 400008 394009 392014 394019 396023 400027 406035 409045 412053 407056 401056 400059 399062 399066 402071 404073 407076 412078 419076 422079 424084 425094 427098 427101 415111 411111 410104 408102 406106 404119 405125 406125 407121 411119 417124 417129 416134 413145 410149 406151 401149 399153 397156 397159 400159 403157 406157 407160 405167 407172 411172 416168 417172 416175 415177 419177 425171 429172 432170 430166 428162 427154 429147 432144 436142 435150 439160 445167 449174 451180 446180 442182 440185 438192 437197 439200 441205 417200 412204 409206 406205 397200 394199 390195 385193 382191 378189 372190 371195 372198 372202 367201 359203 354205 347209 341216 337236 338241 339244 344245 347244 354242 363241 372243 379247 385256 389264 392273 396280 400286 406292 411294 414293 417292 421290 428286 433279 438267 439255 439247 442242 442235 443231 450226 452224 452218 449214 449208 452203 454196 456191 460186 463178 0.01 345007 346001 344997 340998 337001 325005 311012 303012 299013 296014 293017 289018 284020 279023 276028 281031 287031 304031 318028 323025 331025 337028 343028 345025 345020 345010 345007 0.01 276792 273788 268786 263786 257788 246790 242793 238798 235807 234813 235818 238821 241827 245830 251830 255829 261827 265825 268821 274812 276807 278800 276792 0.25 537166 538150 537141 537136 536132 534117 532111 531106 529101 529097 526093 523091 522096 520106 520115 519129 517148 518153 520158 526169 531173 533174 536171 537166 0.25 465663 464659 461656 460655 458654 456654 453654 452654 450656 450657 448661 448663 450666 451667 453669 456670 457670 459670 462669 464666 465663 0.25 499879 498886 499894 503906 508908 507901 504886 503883 502879 502878 499879 0.25 476889 479901 484914 489922 495920 494907 490890 486873 483855 480836 477812 472797 470803 469814 466833 469857 470869 474881 476889 0.25 422270 425264 426259 427254 428251 429247 430244 430242 429241 429238 427237 425235 423234 421234 421232 418231 416231 415230 413229 413227 413225 414224 416221 416218 415215 412214 410215 408215 407213 405212 404212 403213 401212 400210 399208 397206 394204 391202 388202 385202 383201 380201 379203 379206 379210 376213 374214 371214 370215 369216 3672