Quantitative Precipitation Forecast
Issued by NWS

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000
FXUS04 KWBC 270659
QPFPFD

QUANTITATIVE PRECIPITATION FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT FRI MAR 27 2015


PRELIM DAY 1 QPF DISCUSSION
VALID MAR 27/1200 UTC THRU MAR 28/1200 UTC
REFERENCE AWIPS GRAPHICS UNDER...PRECIP ACCUM - 24HR


DAY 1

...EASTERN SEABOARD INTO CENTRAL AND SOUTH FLORIDA...

AT 06Z FRIDAY A COLD FRONT STRETCHED FROM SOUTHERN VIRGINIA TO THE
FAR WESTERN FLORIDA PANHANDLE. THE PRIMARY WARM CONVEYOR BELT AND
PLUME OF SUB-TROPICAL MOISTURE WAS OFFSHORE...WELL IN ADVANCE OF
THE SURFACE FRONT...OWING TO BROAD HEIGHT FALLS AND DEEP LAYER
Q-VECTOR CONVERGENCE EXTENDING OUT OVER THE GULF STREAM.
THEREFORE...WHATEVER RAIN WAS FALLING EARLY FRIDAY MORNING WAS
GENERALLY NON THUNDERY AND ROOTED AT MID LEVELS ACROSS THE EASTERN
U.S. THIS EXCEPTION WAS THE FLORIDA PENINSULA...WHERE GULF
MOISTURE WAS PUSHING EASTWARD AHEAD OF THE TAIL END OF THE UPPER
TROUGH. HEIGHT FALLS WILL STILL BE RATHER SUBSTANTIAL EVEN AT THE
LATITUDE OF FLORIDA TODAY...AND THE LATEST HIGH RESOLUTION MODELS
DEPICT AN ORGANIZED LINE OF CONVECTION FORMING BY LATE MORNING
OVER CENTRAL FLORIDA. TO ACCOUNT FOR ONGOING CONVECTION AND
ASSOCIATED OUTFLOWS...WE PLACED DAYTIME/AFTERNOON QPF FARTHER
SOUTH...TOWARD THE WRF-ARW AND NMM SOLUTIONS WITH AN AXIS OF
1-INCH PLUS RAINFALL GENERALLY SOUTH OF INTERSTATE 4 AND NORTH OF
ALLIGATOR ALLEY. AMOUNTS DROP OFF FARTHER SOUTH OWING TO THE
ANTICIPATED INCREASE OF UPPER WIND SPEEDS AND BROAD COLD POOL
DEVELOPMENT WHICH SHOULD MOVE THINGS ALONG...ESPECIALLY WITH LOW
LEVEL INFLOW BEING SO STRONGLY VEERED.

FARTHER NORTH...LIGHT RAIN IN THE ENTRANCE REGION OF A NORTHERN
STREAM UPPER JET WILL PROGRESS FROM THE MID ATLANTIC INTO SOUTHERN
NEW ENGLAND EARLY THIS MORNING...PRODUCING ROUGHLY .10-.20 INCH
PER HOUR RATES. BY MID MORNING EMPHASIS WILL SHIFT TO A GROWING
REGION OF RAINFALL OVER THE CAROLINAS AND SOUTHERN VIRGINIA AS
SOME STREAM PHASING TAKES PLACE AT UPPER LEVELS. AGAIN...THIS
ACTIVITY SHOULD BE MAINLY NON THUNDERY...WHICH WILL CUT DOWN ON
RAIN RATES...EXCEPT PERHAPS NEAR THE COAST OF NORTH AND SOUTH
CAROLINA WHERE SOME WEAK CONVECTIVE ENHANCEMENT COULD TAKE PLACE.

THE MODELS PREDICT SOME MEASURABLE PRECIPITATION FROM LOW-TOPPED
CONVECTIVE SHOWERS BENEATH THE COLDEST MID LEVEL TEMPERATURES THIS
AFTERNOON IN EASTERN TN/KY AND ADJACENT WESTERN SLOPES OF THE
APPALACHIANS. IT IS DOUBTFUL THIS ACTIVITY WILL BE VERY
EFFICIENT...GIVEN SUCH COOL AND DRY LOW LEVEL AIR...WITH THE NAM
INDICATING ROUGHLY LOWER 40S T OVER UPPER 20S/LOW 30S TD.

OVER THE EASTERN U.S. THE WPC DAY 1 QPF MOST CLOSELY RESEMBLES THE
00Z NAM AND OUR IN-HOUSE ENSEMBLE WHICH TAKES A SMART CONSENSUS OF
THE GLOBAL MODELS AND NAM/SREF. WE ADJUSTED THE PRECIP AXIS
SOUTHWARD IN FLORIDA...CLOSER TO THE ARW AND NMM.


...PACIFIC NORTHWEST...

THE TROUGH COMING INTO THE NORTHWEST FRI/FRI NIGHT CARRIES
IMPRESSIVE 100-METER PER 12 HOUR HEIGHT FALLS. IT IS...HOWEVER...A
SHORT WAVELENGTH TROUGH WITH ENHANCED FLOW MORE MORE SOUTHERLY
THAN WESTERLY PRIOR TO TROUGH PASSAGE. SUBSIDENCE WILL BE SHARP IN
THE WAKE OF SUCH A WAVE WHEN FLOW DOES TURN MORE WESTERLY/ONSHORE.
PRECIPITABLE WATER VALUES AHEAD OF THE TROUGH ARE NOT ESPECIALLY
ANOMALOUS...AT 1 TO 2 STANDARD DEVIATIONS FROM CLIMATOLOGY.
WEIGHING THESE FACTORS...THE MODELS LOOK REASONABLE...AND ARE IN
FAIRLY GOOD AGREEMENT...INDICATING 24-HOUR LIQUID AMOUNTS UNDER
ONE INCH AT MOST LOCATIONS. GIVEN THE STRONG HEIGHT FALLS...WE
LEANED TOWARD GUIDANCE WHICH EXTENDED MEASURABLE PRECIPITATION AS
FAR SOUTH AS WE COULD FIND...INTO NORTHERN CALIFORNIA. THIS
INCLUDED THE 00Z NAM CONEST AND 00Z CANADIAN GEM REGIONAL MODEL.


...EASTERN DAKOTAS TO MISSOURI/ARKANSAS...

ONE DISTURBANCE IN NORTH/NORTHWEST FLOW HEADING INTO KANSAS THIS
MORNING...AND ANOTHER PROGRESSING FROM THE DAKOTAS TO MISSOURI
THROUGH SATURDAY MORNING...WILL YIELD A MORE OR LESS CONTINUOUS
SWATH OF LIGHT PRECIPITATION AMOUNTS BENEATH A MID LEVEL
BAROCLINIC ZONE. THE PREVIOUS WPC FORECAST HANDLED THIS WELL...AND
WE BLENDED TOWARD THE 00Z NAM AND 18Z GEFS.

BURKE

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

24HR QP VT 28/12Z
 0.01 527251 523242 519232 534217 537213 539208 540202 541195
      539189 536183 529172 521153 518148 514144 509140 504139
      498138 494135 488128 482127 477128 473128 467131 454142
      446150 439156 437160 438164 441169 441175 438179 435183
      428182 425182 423184 422191 419194 411199 408203 408210
      405213 404221 404231 403237 401241 401247 405252 405258
      409263 413266 418267 428268 434270 438271 440269 446270
      451270 455270 458272 468278 473280 480283 493287 518282
      527251
 0.01 516214 517211 517209 516206 515204 513205 512205 510205
      508205 507206 507208 508210 508211 509213 511214 511215
      512216 513216 514215 515215 516214
 0.01 518015 518008 517005 514999 511994 506988 501983 496979
      489974 483969 477967 471966 464964 458962 453958 449952
      444946 437942 413931 401922 396917 389913 379909 372907
      366909 362909 360908 359905 353900 350891 347886 340874
      337873 337876 338886 339888 340894 341902 344912 349919
      351926 354931 356934 357938 357949 361956 364961 370967
      375972 386979 389980 391981 398982 396975 392970 386965
      382962 379958 375953 378950 382950 387952 391954 393958
      394962 396965 401968 407973 412975 416976 418978 422978
      427982 439987 450993 465001 476007 482011 486015 493019
      499024 505027 511024 516020 518015
 0.01 483189 482186 481188 482189 483189
 0.01 456648 455643 451642 442645 434644 423648 419650 413652
      406658 401662 396665 391669 388672 378686 367700 360707
      356712 351715 334726 319735 313742 309748 304757 298760
      290760 286759 280760 268762 258764 251768 243773 236778
      231784 229789 229794 229803 228808 225819 224823 225828
      226833 229835 233837 240840 249845 252853 263855 280848
      292839 296836 298833 303826 308825 312823 317814 322812
      322821 327830 343831 345831 346835 346842 351846 357847
      360850 362856 364854 366844 363838 368834 374828 378822
      381814 387806 391804 396803 398800 401800 404797 408793
      408787 406785 404785 400788 385796 388786 391777 394767
      400756 410738 422726 432723 435720 437716 440706 438702
      438695 439687 442682 444676 446671 456648
 0.01 453740 452733 448731 441731 434734 430732 427729 425729
      426734 426738 428741 429745 427748 431755 432759 434761
      434765 433768 428770 419764 412758 411758 411763 412772
      414777 413783 412786 412791 413800 415809 414812 414816
      419816 424808 428802 432797 437789 440784 442776 449753
      452747 453740
 0.01 448831 448824 445824 441822 436823 429824 422825 418827
      422830 428831 433833 435835 438835 445834 448831
 0.01 426871 426869 423869 421867 417867 414868 410868 410870
      412873 414873 416875 419875 423874 425872 426871
 0.01 423839 423834 419834 416832 413828 409823 404819 402818
      397818 393819 391822 391827 392833 396839 397842 400846
      402848 406848 414847 419842 423839
 0.25 535204 535201 534199 532198 530198 530199 529202 528204
      528207 528210 529212 530212 532211 532210 533209 534206
      535204
 0.25 522264 522258 521252 516239 510230 501220 498209 493206
      488206 483205 478207 469212 460215 456217 452221 456229
      455231 452233 448235 445239 448243 455245 461245 466246
      470249 481256 484260 483265 482270 484272 490274 495277
      501279 512277 515276 518273 521267 522264
 0.25 518183 518170 517163 514160 511162 509164 507163 504161
      501161 496163 491168 487165 485159 482156 479154 469153
      464154 462158 462162 461167 458171 453178 451184 451191
      453193 455192 459190 467184 474184 480173 482168 485169
      492177 494180 499181 504179 509183 514188 518183
 0.25 508156 508154 507153 506152 505153 504154 503155 503158
      503159 505160 506159 507158 508156
 0.25 444218 444217 442216 441217 441220 442220 443218 444218
 0.25 426669 425663 424660 418657 414659 407664 395673 389680
      384688 376700 372706 367710 361716 354722 345725 338729
      327738 322743 319748 315755 309763 304768 296772 292772
      289770 287768 284768 282769 280773 277779 270785 260787
      254791 246794 239804 233817 231825 234830 236829 247819
      251817 252820 253829 254838 257845 260847 266846 273843
      280838 285831 301810 312798 326788 331785 335784 337785
      339788 339792 341798 343801 347802 351802 358797 364796
      370793 376789 379782 380778 378776 375767 375761 376757
      379749 384742 390736 398725 406712 416697 423682 425676
      426669
 0.50 519265 519258 517250 516244 512239 509234 502231 498236
      499245 501251 500254 498252 495248 488245 486248 487252
      488259 488267 494272 498275 504276 506272 506268 511271
      515270 519265
 0.50 496223 497216 496211 492212 487212 484212 479212 475214
      477216 481219 484222 487225 492225 496224 496223
 0.50 480244 481241 480240 479239 477238 475239 475240 476242
      476243 478244 480244 480244
 0.50 472218 471217 470217 468217 467217 466219 466220 467222
      469221 470220 471219 472218
 0.50 470168 469165 467167 466169 465170 464171 465173 467172
      468170 469169 470168
 0.50 411676 410671 408671 402675 394678 390684 383695 379702
      374708 353725 347728 341731 334736 329741 323751 321755
      321760 317765 315772 315780 318782 322783 327779 332774
      336771 340770 346769 350768 352765 357761 360756 363747
      366741 375732 385720 391709 399696 411676
 0.50 291805 292798 290794 286794 272796 267794 264793 261795
      260800 264804 260815 257820 256824 256828 261840 262842
      266842 272839 276837 280832 283828 285823 286817 289811
      291805
 0.50 247808 245805 243805 240809 238812 236816 234820 233824
      234826 238824 241819 243817 246813 247809 247808
 1.00 515264 516258 515253 514248 512243 509240 505240 504242
      504249 505255 506259 509263 512266 515264 515264
 1.00 503273 503268 502265 501261 499259 498258 495255 492254
      491258 491261 492265 493267 496270 498271 501273 503273
 1.00 367721 366718 365720 363723 362726 361728 359731 359734
      360737 361734 363733 364730 366726 366723 367721
 1.00 349738 348735 345737 342744 338750 333754 328761 325768
      326770 329767 334762 341757 344752 346745 349738
 1.00 283811 281804 278803 272806 268810 264815 261819 261825
      262827 265828 269824 274821 279817 282813 283811
 1.50 511260 512258 513255 512253 512252 511249 511247 510245
      508244 506245 506247 506250 506253 507255 507256 508257
      509259 511260 511260
 1.50 502270 502267 500264 499262 498260 497260 496259 494258
      494259 493261 494264 495266 496267 497268 498269 499270
      501270 502270
 1.50 267822 268820 270818 274814 275811 274809 273809 272811
      269814 266817 265819 265821 267822

$$




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