Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 020626
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
225 AM EDT SUN AUG 02 2015


PRELIM DAY 1 QPF DISCUSSION
VALID AUG 02/1200 UTC THRU AUG 03/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1...


...SOUTHEAST/FL...

DEEP TROPICAL MOISTURE AND INSTABILITY WILL FEED SURGES OF
CONVECTION THAT TRACK ALONG A SURFACE TROUGH FROM THE EASTERN GULF
OF MEXICO ACROSS PORTIONS OF NORTHERN FL DURING DAY 1...PRODUCING
HEAVY TO EXCESSIVE RAINFALL. THE 00Z NAM APPEARS TO BE TOO QUICK
TO SCOUR THE MOISTURE AND DEVELOP A SURFACE WAVE ON THE
TROUGH...RESULTING INTO TOO LITTLE QPF FOR NORTHERN FL...GIVEN THE
MOISTURE PROFILE. THERE IS SOME SPREAD BETWEEN THE 00Z GFS AND 12Z
ECMWF CONCERNING THE POSITION OF THE MAXIMUM QPF (WITH 00Z GFS A
BIT FURTHER NORTH...THE 12Z ECMWF A BIT FURTHER SOUTH). EACH
SOLUTION HAS SUPPORT FROM OTHER MODELS...WHICH LEADS TO A BELOW
AVERAGE CONFIDENCE CONCERNING THE PLACEMENT OF THE MAXIUM QPF. FOR
NOW...A SOLUTION CLOSER TO THE 00Z GFS WAS PREFERRED...AS THIS IS
WHERE THE BEST LOW LEVEL CONVERGENCE IS EXPECTED.

THERE IS A LULL IN THE CONVECTION ACROSS PORTIONS OF NORTHERN AND
CENTRAL FL EARLY THIS MORNING...AS THE BEST MEAN LAYER INSTABILITY
REMAINS OFF THE WEST COAST OF THE PENINSULA. THE ACTIVITY SHOULD
REDEVELOP CLOSER TO 02/12Z...AS INSTABILITY INCREASES...AND THE
2.50 INCH PRECIPITABLE WATER PLUME OFF THE WEST COAST SURGES
EASTWARD. THE BEST LOW LEVEL MOISTURE FLUX IS CENTERED AROUND
02/18Z...AND SLOWLY TAILS OFF AFTER THAT TIME. THE BEST CONVECTION
IS EXPECTED BETWEEN 02/12Z AND 03/00Z...AFTER WHICH THE BEST LOW
AND MID LEVEL MOISTURE SHOULD BEGIN TO SLIDE TO THE EAST. THE HIGH
MOISTURE CONTENT OF THE AIR (ABOUT TWO STANDARD DEVIATIONS ABOVE
THE MEAN)...AS WELL AS THE POTENTIAL FOR TRAINING ACROSS PORTIONS
OF THE NORTHWEST PORTION OF THE PENINSULA...INDICATES THAT A BASIN
AVERAGE OF 3 TO 4 INCHES OF QPF SHOULD BE EXPECTED BETWEEN KCTY
AND KBKV.

AS MENTIONED EARLIER...THERE IS SOME SPREAD ON WHERE THE QPF
MAXIMUM OCCURS. THIS SEEMS TO BE TIED TO THE POSITION OF A SURFACE
TROUGH ALONG THE WEST COAST...AND THE LATITUDINAL DIFFERENCES
RESULT IN A LOWER THAN AVERAGE FORECAST FOR MAXIMUM QPF. IT SHOULD
BE NOTED THAT SOME OF THE 00Z HIGH RESOLUTION GUIDANCE...SUCH AS
THE 00Z WRF ARW AND 00Z REGIONAL GEM...SHOW THE POTENTIAL FOR AN
ADDITIONAL 6 TO 9 INCHES OF RAINFALL WHERE TRAINING OCCURS. LIKE
THE DIFFERENCES BETWEEN THE 00Z GFS/12Z ECMWF...THE HIGH
RESOLUTION GUIDANCE ALSO SHOWS SPREAD ON THE PLACEMENT OF MAXIMUM
QPF. GIVEN THE SPREAD IN PLACE...A SLIGHT RISK AREA WILL BE PLACED
OVER MUCH OF THE WESTERN PORTION OF THE PENINSULA FROM KTPA
NORTHWEST INTO THE BIG BEND AREA.

OVER THE EAST COAST OF FL...LOW LEVEL CONVERGENCE ALONG A SURFACE
BOUNDARY/SEA BREEZE SHOULD PROVIDE A FOCUS FOR CONVECTION FROM
KTTS THROUGH KFPR. THERE IS A MULTI MODEL SIGNAL FOR A SWATH OF
0.75 TO 1.00 INCHES OF QPF ALONG THIS AXIS. HIGH RESOLUTIONS
GUIDANCE (SUCH AS THE 00Z WRF NMMB) SUGGEST LOCALLY HIGHER AMOUNTS
(CLOSE TO 2.00 INCHES) ARE POSSIBLE.


...MIDWEST/GREAT LAKES/OH VALLEY...

MOISTURE AND INSTABILITY AHEAD OF A COLD FRONT CROSSING THE GREAT
LAKES AND MIDWEST DURING DAY 1 WILL FEED DEVELOPING
CONVECTION...WHICH MAY PRODUCE LOCALLY HEAVY RAINFALL...ESPECIALLY
ACROSS THE GREAT LAKES. THE 00Z NAM APPEARS TO BE TOO AGGRESSIVE
WITH THE DEVELOPMENT OF A SURFACE WAVE ON THE FRONT ACROSS
MI...WHICH LEADS TO STRONG LOW LEVEL CONVERGENCE AND A WELL
DEVELOPED CONVECTIVE LINE WITH HEAVY RAINFALL ACROSS THE LP OF MI.
THE 00Z GFS/12Z ECMWF APPEARED TO HAVE A BETTER HANDLE ON THE
TIMING AND STRENGTH OF THE FRONT...AND THE WPC QPF WAS BASED MORE
ON THIS BLEND.

THE FIRST BATCH OF CONVECTION DEVELOPS AHEAD OF A SHORT WAVE THAT
TRACKS OUT OF CENTRAL CANADA INTO THE GREAT LAKES BEFORE 02/18Z.
MOISTURE AND INSTABILITY AHEAD OF THE SHORT WAVE SHOULD BE
SUFFICIENT FOR A CLUSTER OF STRONG CONVECTION TO DEVELOP AND MOVE
ACROSS PORTIONS OF EASTERN
IA/NORTHERN AND CENTRAL IL INTO TO THE MID AFTERNOON. WHILE THERE
WILL BE ENOUGH MOISTURE AND LOW LEVEL MOISTURE FLUX FOR LOCALLY
HEAVY RAINFALL... THE CLUSTER SHOULD BE MOVING WITH THE MID LEVEL
FLOW...SO THE POTENTIAL FOR ORGANIZED FLASH FLOODING DURING THIS
TIME IS LOW.

THE MAIN THREAT FOR HEAVY RAINFALL COMES AFTER 02/18Z...AS A
STRONG SHORT WAVE DIVING SOUTH FROM CENTRAL CANADA CROSSES THE
UPPER GREAT LAKES. AHEAD OF THE SHORT WAVE AND SURFACE COLD
FRONT...A 40 TO 50 KNOT LOW LEVEL SOUTHWEST INFLOW TRANSPORTS
PRECIPITABLE WATER NEAR 1.50 INCHES INTO THE GREAT LAKES (MAINLY
WI/MI). MODEL SOUNDINGS SHOWED THAT INITIALLY DRY MID LEVELS
MOISTEN...SUGGESTING THAT THE COLUMN BECOMES MORE CONDUCIVE TO
HEAVY RAINFALL. THE MAIN THREAT FOR HEAVY RAINS SHOULD BE CENTERED
IN THE 30/00Z THROUGH 03/06Z TIME FRAME...AND A LARGE AREA OF 0.75
TO 1.25 INCHES OF QPF WAS PLACED OVER MI AND SOUTHEAST WI.

IT SHOULD BE NOTED THAT MOST GLOBAL/REGIONAL MODELS HAD MAXIMUM
QPF VALUES IN EXCESS OF 2.00 INCHES...THOUGH IN DIFFERENT
LOCATIONS (MAINLY ACROSS THE LP OF MI INTO NEARBY ONTARIO). THREE
HOUR FLASH FLOOD GUIDANCE VALUES ARE GENERALLY ABOVE 2.00
INCHES...AND THE 14 DAY PRECIPITATION TOTALS HAVE BEEN RELATIVELY
LIGHT...SUGGESTING DRY ANTECEDENT CONDITIONS. WHILE THE MOISTURE
PROFILE IS IMPRESSIVE...THE STORMS THAT DEVELOP SHOULD MOVE WITH
THE MID LEVEL FLOW...SO OUTSIDE OF TRAINING...THE THREAT FOR
ORGANIZED FLASH FLOODING APPEARS TO BE LOW.


...WESTERN UNITED STATES...

MONSOONAL MOISTURE CONTINUES TO SURGE INTO THE SOUTHWEST
STATES...AND PORTIONS OF THE MOISTURE ARE DIVERTED INTO THE GREAT
BASIN AND SOUTHERN PLAINS. THE HIGH MOISTURE CONTENT
AIR...COMBINED WITH MARGINAL INSTABILITY AND LIFT FROM A SHORT
WAVE ACROSS THE SOUTHERN ROCKIES AND GREAT BASIN...IS EXPECTED TO
PRODUCE AN AREA OF SCATTERED TO BROKEN CONVECTION ACROSS THE AREA.
CONVECTION COULD PRODUCE HEAVY TO LOCALLY EXCESSIVE
RAINFALL...ESPECIALLY ACROSS PORTIONS OF THE SOUTHERN ROCKIES AND
GREAT BASIN. FOR THE MOST PART...THERE WAS GOOD MODEL AGREEMENT
WITH THE OVERALL SYNOPTIC SETUP...INCLUDING THE PLACEMENT OF THE
SHORT WAVE. WITH THIS IN MIND...THE WPC QPF WAS BASED ON A BLEND
OF THE 00Z NAM/GFS/12Z ECMWF...AND WAS AUGMENTED BY THE 00Z WRF
ARW TO BETTER DEPICT HIGHER TERRAIN QPF MAXIMA.

CONVECTION CONTINUES TO DEVELOP ACROSS PORTIONS OF EASTERN NM
EARLY THIS MORNING...WHICH THEN TRACKS INTO NORTH TX. INSTABILITY
REMAINS IN PLACE ACROSS THE AREA...BUT THE LOW LEVELS CONTINUE TO
STABILIZE...SO ADDITIONAL DEVELOPMENT SHOULD BE ON THE NOSE OF LOW
LEVEL JET ACROSS WEST TX THROUGH 02/12Z OR SO. ADDITIONAL ACTIVITY
DOES NOT APPEAR TO HAVE ENOUGH INSTABILITY FOR A SUSTAINED HEAVY
RAIN THREAT. ADDITIONAL ACTIVITY IS EXPECTED ACROSS ACROSS EASTERN
NM DURING THE DAY ...AS PRECIPITABLE WATER VALUES NEAR AN INCH
FUEL CONVECTION THAT IS INITIALLY TIED TO THE TERRAIN.

CLUSTERS THAT DEVELOP IN EASTERN NM COULD SURVIVE INTO THE EVENING
HOURS...BEFORE FOLLOWING AN INSTABILITY AXIS ACROSS NORTH TX INTO
SOUTHWEST OK. THE LATEST NAM SIMULATED SATELLITE IMAGERY SUGGESTS
THAT A SMALL MCS COULD FORM ON THE NOSE OF A LOW LEVEL JET ACROSS
WEST TX IN THE 03/6Z TO 03/12Z TIME FRAME. WHILE AN MCS COULD
FORM...THERE IS NOT A STRONG MULTI MODEL SIGNAL FOR IT TO OCCUR.
THEREFORE...THE 00Z NAM MAY BE TOO HEAVY WITH ITS QPF ACROSS NORTH
TX...AND THE WPC QPF WAS BASED MORE CLOSELY ON A BLEND ON THE 00Z
GFS/12Z ECMWF HERE.

THE BEST THRUST OF MONSOONAL MOISTURE SHOULD OCCUR ACROSS NM INTO
THE SOUTHERN ROCKIES AND GREAT BASIN (AS SEEN ON THE LATEST HIGH
AND MID LEVEL LAYERED PRECIPITABLE WATER IMAGES). THERE IS GOOD
MODEL AGREEMENT THAT A SHORT WAVE TRACKS NORTH OUT OF AZ THROUGH
NV AND UT DURING THE AFTERNOON AND EVENING HOURS. THE SYNOPTIC
SCALE ASCENT ASSOCIATED WITH THE SHORT WAVE SHOULD ALLOW CLUSTERS
OF CONVECTION TO BLOSSOM ACROSS WESTERN CO (INCLUDING THE SAN JUAN
MOUNTAINS) INTO NEARBY SOUTHEAST UT. PRECIPITABLE WATER VALUES
HERE SHOULD RANGE BETWEEN TWO AND THREE STANDARD DEVIATIONS  ABOVE
THE MEAN...INCREASING THE THREAT FOR FLASH FLOODING. SOME OF THE
HIGH RESOLUTION GUIDANCE SUGGESTS LOCAL 2.00 INCH QPF AMOUNTS ARE
POSSIBLE WITH STORMS THAT TAP THE HIGH MOISTURE AIR...AND BASED ON
WHAT OCCURRED ACROSS WESTERN CO SAT...THIS SEEMS PLAUSIBLE.

THERE IS SOME UNCERTAINTY CONCERNING HOW WIDESPREAD THE HEAVY RAIN
THREAT WILL BE...BUT WESTERN CO AND SOUTHEAST UT SEEM TO BE IN THE
AREA WITH THE BEST COMBINATION OF LIFT/MOISTURE. WHILE BASIN
AVERAGE QPF AMOUNTS BETWEEN 0.25 AND 0.50 INCHES MAY BE COMMON IN
THE HIGHER TERRAIN...HIGHER AMOUNTS IN AREAS WHERE ONE AND THREE
HOUR FLASH FLOOD GUIDANCE VALUES ARE AN INCH OR LESS WILL CAUSE
PROBLEMS. EITHER A SEE TEXT OR SMALL SLIGHT RISK AREA WILL BE
ISSUED FOR THIS AREA...WHICH MAY DEPEND ON COLLABORATION WITH
LOCAL OFFICES.

FURTHER WEST...INSTABILITY AND MOISTURE COULD SUPPORT SCATTERED
CONVECTION WITH LOCALLY HEAVY RAINFALL ACROSS PORTIONS OF NV INTO
NORTHERN CA AND WESTERN OR. AT THIS POINT...THE COVERAGE DOES NOT
APPEAR TO BE SUFFICIENT FOR A SLIGHT RISK AREA...BUT THIS WILL BE
MONITORED.


HAYES

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

24HR QP VT 03/12Z
 0.01 502317 501314 502312 503312 504310 505310 516281 515278
513277 512274 511270 512265 512260
      514258 516257 518255 520253 522251 524249 526247 526244
      528242 530240
 0.01 553146 554133 555125 557117 556111 553107 542105 538106
      535110 530109 528103 523097 520099 516104 514105 512100
      509097 505101 500108 497115 498121 498135 499141 501147
      504152 508155 516163 521172 523177 525185 526191 526198
      529198 532192 536191 539193 538198 536205 536209 537212
      537215 544190 543190 541192 539194 538191 538188 539186
      540184 541181 541178 542176 544179 545180
 0.01 547928 547905 546879 545856 544847 543834 536795 534792
      533787 531781 528775 524775 521778 518782 515789 513797
      512801 509805 505818 501837 502856 506872 509880 511887
      518902 528931 534945 535947 539947 544941 544933 547928
 0.01 517660 513656 510653 507652 504652 499653 493658 481674
      476681 470687 465692 460699 456706 451714 448722 443730
      432744 418776 412793 409804 406815 402833 399840 396843
      392846 389847 388852 385862 382873 382886 374899 374902
      378905 380907 380911 380917 378923 380929 380934 382938
      387943 390944 389947 388951 385958 385965 385970 386975
      388980 394986 397986 401983 405975 409967 413959 416952
      419943 421940 422934 425924 426919 429915 432912 436912
      455915 472917 475915 477911 481902 484891 486879 488869
      490859 494836 495825 496813 495798 495791 493787 492783
      495779 500773 510759 533731 533726 534722 533706
 0.01 446226 445221 443215 439211 437206 433203 427200 415198
      413195 413192 416187 417168 416160 412156 410152 409147
      411143 413130 416114 418108 418099 419093 418083 414066
      416064 416059 414053 410050 407045 400035 400028 400024
      399023 397023 395026 392031 387035 383035 382032 379026
      379021 377011 373006 371001 367999 366996 366991 368990
      364985 355980 345977 341976 336979 332983 330990 329996
      329003 331011 330016 328025 330030 335034 337036 338040
      338048 337052 336055 319043 316046 318050 326059 337064
      336067 334068 331068 326068 320068 315071 309070 304071
      284064 279063 274061 268059 260058 254056 247055 237053
      234056 235060 238065 243070 247073 253081 261087 266089
      273090 280091 283093 283097 286102 291106 296109 302114
      311121 321126 322128 326124 325118 327113 331113 335116
      338122 341127 346132 349131 351128 355122 357120 357115
      354110 353108 356107 363106 363114 364119 362125 365129
      362136 356144 355149 356152 359157 367167 368169 368174
      368179 366182 361184 364185 367187 371189 372192 378199
      383203 387207 392210 397215 401219 403224 404227 404232
      407239 412241 415243 418245 423246 425243 424234 428230
      432228 437227 446226
 0.01 385675 369679 360681 355688 348693 342699 332713 324726
      318741 309756 305763 300770 295774 285777 281777 278779
      268781 252788 246805 245807 245811 247815 250818 256817
      260818 263820 266823 267826 264835 262839 262844 263856
      265877 266899 266908 265919 264929 261939 259945 258956
      257965 257968 260966 264963 269962 274958 284943 287938
      290934 294933 299933 301930 301925 303922 302899 306891
      307886 307882 308865 313849 321834 325827 328823 334822
      339818 342815 343811 345801 348794 354778 362760 376731
      382716 384712 385706 384699 385694 385675
 0.01 386747 384746 381747 379750 378753 378755 376758 375760
      375765 376765 379762 381760 382759 384754 385754 385749
      386747
 0.25 504723 503715 499711 494714 489718 480724 477726 474726
      468726 459731 456734 452740 447750 441761 436770 431781
      420804 416813 412824 408836 407843 406852 407863 405876
      404884 402889 397892 393897 394904 396908 403917 406919
      408914 412917 415918 417916 424907 429898 432893 436889
      440885 444885 449884 454882 456878 459871 462859 465844
      467829 470817 476787 482764 484759 487754 495744 498739
      501734 504723
 0.25 475892 475886 473880 471878 469870 467866 465867 464870
      463876 464883 465890 465895 467901 471900 473895 475892
 0.25 416229 418225 418220 418216 416213 414212 411210 408211
      407215 408218 410220 411225 411228 413230 416229
 0.25 409110 410104 409098 406098 404104 401108 397108 392105
      388102 392091 392078 393074 397071 398063 397059 394055
      388049 377046 372044 367041 364033 364025 365014 364007
      359007 351009 348013 348020 350025 353028 360036 362040
      360046 356056 357058 360058 364056 369056 375056 379059
      377062 373062 369060 366063 362063 359062 357063 357067
      360071 363073 368080 370086 373090 375094 377100 379103
      381105 384105 386105 385110 382109 379112 375123 373127
      372132 378132 381131 388125 391121 396119 402113 407112
      409110
 0.25 394177 396173 397168 396164 394162 391161 389163 387166
      386168 385173 386175 387178 390180 392179 394177
 0.25 390201 388199 386196 385194 383192 382190 379187 377186
      376188 378190 380192 383194 384196 386198 389201 390201
 0.25 365730 365726 364722 363718 361716 359715 358711 356708
      354708 351709 342712 338717 332730 320750 313762 306776
      300785 297790 295792 292794 284794 276797 261801 256804
      254806 256808 266812 274813 277814 278818 274824 272830
      271836 271845 272863 274880 275890 275900 273906 273913
      273922 272929 270942 270946 272948 274946 276942 280930
      282924 282914 284906 286900 289894 291886 310834 315823
      322812 330802 337791 349768 360742 365730
 0.25 368093 368090 368088 366086 364086 363085 362085 361086
      359086 358087 359089 360091 361092 362093 363094 363095
      365095 367095 367094 368093
 0.25 352991 351991 350991 348991 349991 351991 352991
 0.25 341098 341096 341093 340092 339091 337092 336093 337093
      337095 338097 338098 340098 341098
 0.25 336086 336084 334084 333086 333087 335087 336086
 0.25 331081 332079 331078 329079 330081 330082 331081
 0.25 300084 300082 299081 297081 296080 294080 292081 293083
      293084 295086 297086 299086 300084
 0.50 472761 471756 469754 464756 459763 457766 454769 448771
      443776 438783 434790 427802 423808 420818 416833 413841
      414847 415851 415862 415871 415877 417880 416886 413893
      412901 413910 415909 418905 421899 425893 429886 430880
      432877 437873 440872 443873 447874 450872 454864 456856
      456846 459825 460816 460806 463785 465777 467772 472761
 0.50 415227 415224 414223 413224 414226 414227 415227
 0.50 381081 382078 382076 382074 382072 381072 380070 379069
      378069 376068 375067 374069 374071 374073 374075 374077
      374078 374080 375082 377082 379082 381081 381081
 0.50 356730 352723 348723 343725 336729 331737 324750 320757
      316765 310778 306786 303795 302804 301813 298815 295813
      291812 288815 282819 277824 275828 274832 273838 274845
      277864 278869 281871 284870 287866 297855 303840 306832
      309825 309820 311816 317811 327799 336786 350756 353751
      354744 356730
 0.50 293805 292803 289801 287800 284800 281800 278801 276802
      272803 270804 270808 272810 275811 278811 282810 286809
      289809 292807 293805
 1.00 448817 447814 447812 447811 445810 443808 442808 440808
      440810 440813 441815 441817 442819 443820 444822 445822
      446821 447819 447818 448817
 1.00 447860 446860 446858 445856 443858 443860 443861 443863
      445863 446863 446861 447860
 1.00 346752 346747 344743 342744 339748 337750 337747 339743
      338740 334745 331751 328758 327762 325766 321771 317777
      311790 310797 312801 316801 321796 325790 334779 338773
      340766 343759 346752
 1.00 302829 301827 298824 292820 289819 285820 280825 277832
      277838 278848 279853 282856 284857 288856 292850 296845
      300838 302830 302829
 1.50 335765 334763 332765 332768 333769 334767 335765
 1.50 332772 332770 331769 331770 330772 331772 332772
 1.50 327779 327777 326776 324777 323777 323778 322780 321780
      320782 320783 319785 320786 322785 323784 323783 325782
      325781 327779 327779
 1.50 299836 300832 298828 294825 289823 285823 283825 280830
      280838 280846 283851 287851 290849 293845 296840 299836
 2.00 299834 298830 294827 291826 286827 283829 282834 282840
      283845 285848 289847 292844 295841 297837 299834
 3.00 297834 297832 295830 293829 292828 291828 289828 289829
      287830 286831 286833 286835 286837 286839 288840 290840
      292840 293839 294839 295837 296836 297834 297834

$$





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